diff --git a/Cargo.lock b/Cargo.lock
index c7185c2..3129b6c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -979,6 +979,7 @@ dependencies = [
  "ropey",
  "serde",
  "serde_json",
+ "thiserror",
  "tokenizers",
  "tokio",
  "tower-lsp",
diff --git a/crates/llm-ls/Cargo.toml b/crates/llm-ls/Cargo.toml
index 7ac7cec..f70e218 100644
--- a/crates/llm-ls/Cargo.toml
+++ b/crates/llm-ls/Cargo.toml
@@ -18,6 +18,7 @@ reqwest = { version = "0.11", default-features = false, features = [
 ] }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
+thiserror = "1"
 tokenizers = { version = "0.14", default-features = false, features = ["onig"] }
 tokio = { version = "1", features = [
   "fs",
diff --git a/crates/llm-ls/src/backend.rs b/crates/llm-ls/src/backend.rs
index a139870..c9f18cd 100644
--- a/crates/llm-ls/src/backend.rs
+++ b/crates/llm-ls/src/backend.rs
@@ -1,59 +1,44 @@
-use super::{
-    internal_error, APIError, APIResponse, CompletionParams, Generation, Ide, NAME, VERSION,
-};
+use super::{APIError, APIResponse, CompletionParams, Generation, Ide, NAME, VERSION};
 use reqwest::header::{HeaderMap, HeaderValue, AUTHORIZATION, USER_AGENT};
 use serde::{Deserialize, Serialize};
 use serde_json::{Map, Value};
 use std::fmt::Display;
-use tower_lsp::jsonrpc;
 
-fn build_tgi_headers(api_token: Option<&String>, ide: Ide) -> Result<HeaderMap, jsonrpc::Error> {
+use crate::error::{Error, Result};
+
+fn build_tgi_headers(api_token: Option<&String>, ide: Ide) -> Result<HeaderMap> {
     let mut headers = HeaderMap::new();
     let user_agent = format!("{NAME}/{VERSION}; rust/unknown; ide/{ide:?}");
-    headers.insert(
-        USER_AGENT,
-        HeaderValue::from_str(&user_agent).map_err(internal_error)?,
-    );
+    headers.insert(USER_AGENT, HeaderValue::from_str(&user_agent)?);
 
     if let Some(api_token) = api_token {
         headers.insert(
             AUTHORIZATION,
-            HeaderValue::from_str(&format!("Bearer {api_token}")).map_err(internal_error)?,
+            HeaderValue::from_str(&format!("Bearer {api_token}"))?,
         );
     }
 
     Ok(headers)
 }
 
-fn parse_tgi_text(text: &str) -> Result<Vec<Generation>, jsonrpc::Error> {
-    let generations =
-        match serde_json::from_str(text).map_err(internal_error)? {
-            APIResponse::Generation(gen) => vec![gen],
-            APIResponse::Generations(_) => {
-                return Err(internal_error(
-                    "You are attempting to parse a result in the API inference format when using the `tgi` backend",
-                ))
-            }
-            APIResponse::Error(err) => return Err(internal_error(err)),
-        };
-    Ok(generations)
+fn parse_tgi_text(text: &str) -> Result<Vec<Generation>> {
+    match serde_json::from_str(text)? {
+        APIResponse::Generation(gen) => Ok(vec![gen]),
+        APIResponse::Generations(_) => Err(Error::InvalidBackend),
+        APIResponse::Error(err) => Err(Error::Tgi(err)),
+    }
 }
 
-fn build_api_headers(api_token: Option<&String>, ide: Ide) -> Result<HeaderMap, jsonrpc::Error> {
+fn build_api_headers(api_token: Option<&String>, ide: Ide) -> Result<HeaderMap> {
     build_tgi_headers(api_token, ide)
 }
 
-fn parse_api_text(text: &str) -> Result<Vec<Generation>, jsonrpc::Error> {
-    let generations = match serde_json::from_str(text).map_err(internal_error)? {
-        APIResponse::Generation(gen) => vec![gen],
-        APIResponse::Generations(gens) => gens,
-        APIResponse::Error(err) => return Err(internal_error(err)),
-    };
-    Ok(generations)
-}
-
-fn build_ollama_headers() -> Result<HeaderMap, jsonrpc::Error> {
-    Ok(HeaderMap::new())
+fn parse_api_text(text: &str) -> Result<Vec<Generation>> {
+    match serde_json::from_str(text)? {
+        APIResponse::Generation(gen) => Ok(vec![gen]),
+        APIResponse::Generations(gens) => Ok(gens),
+        APIResponse::Error(err) => Err(Error::InferenceApi(err)),
+    }
 }
 
 #[derive(Debug, Serialize, Deserialize)]
@@ -76,16 +61,15 @@ enum OllamaAPIResponse {
     Error(APIError),
 }
 
-fn parse_ollama_text(text: &str) -> Result<Vec<Generation>, jsonrpc::Error> {
-    let generations = match serde_json::from_str(text).map_err(internal_error)? {
-        OllamaAPIResponse::Generation(gen) => vec![gen.into()],
-        OllamaAPIResponse::Error(err) => return Err(internal_error(err)),
-    };
-    Ok(generations)
+fn build_ollama_headers() -> HeaderMap {
+    HeaderMap::new()
 }
 
-fn build_openai_headers(api_token: Option<&String>, ide: Ide) -> Result<HeaderMap, jsonrpc::Error> {
-    build_api_headers(api_token, ide)
+fn parse_ollama_text(text: &str) -> Result<Vec<Generation>> {
+    match serde_json::from_str(text)? {
+        OllamaAPIResponse::Generation(gen) => Ok(vec![gen.into()]),
+        OllamaAPIResponse::Error(err) => Err(Error::Ollama(err)),
+    }
 }
 
 #[derive(Debug, Deserialize)]
@@ -130,7 +114,7 @@ struct OpenAIErrorDetail {
 }
 
 #[derive(Debug, Deserialize)]
-struct OpenAIError {
+pub struct OpenAIError {
     detail: Vec<OpenAIErrorDetail>,
 }
 
@@ -153,13 +137,16 @@ enum OpenAIAPIResponse {
     Error(OpenAIError),
 }
 
-fn parse_openai_text(text: &str) -> Result<Vec<Generation>, jsonrpc::Error> {
-    match serde_json::from_str(text).map_err(internal_error) {
-        Ok(OpenAIAPIResponse::Generation(completion)) => {
+fn build_openai_headers(api_token: Option<&String>, ide: Ide) -> Result<HeaderMap> {
+    build_api_headers(api_token, ide)
+}
+
+fn parse_openai_text(text: &str) -> Result<Vec<Generation>> {
+    match serde_json::from_str(text)? {
+        OpenAIAPIResponse::Generation(completion) => {
             Ok(completion.choices.into_iter().map(|x| x.into()).collect())
         }
-        Ok(OpenAIAPIResponse::Error(err)) => Err(internal_error(err)),
-        Err(err) => Err(internal_error(err)),
+        OpenAIAPIResponse::Error(err) => Err(Error::OpenAI(err)),
     }
 }
 
@@ -186,20 +173,16 @@ pub fn build_body(prompt: String, params: &CompletionParams) -> Map<String, Valu
     body
 }
 
-pub fn build_headers(
-    backend: &Backend,
-    api_token: Option<&String>,
-    ide: Ide,
-) -> Result<HeaderMap, jsonrpc::Error> {
+pub fn build_headers(backend: &Backend, api_token: Option<&String>, ide: Ide) -> Result<HeaderMap> {
     match backend {
         Backend::HuggingFace => build_api_headers(api_token, ide),
-        Backend::Ollama => build_ollama_headers(),
+        Backend::Ollama => Ok(build_ollama_headers()),
         Backend::OpenAi => build_openai_headers(api_token, ide),
         Backend::Tgi => build_tgi_headers(api_token, ide),
     }
 }
 
-pub fn parse_generations(backend: &Backend, text: &str) -> jsonrpc::Result<Vec<Generation>> {
+pub fn parse_generations(backend: &Backend, text: &str) -> Result<Vec<Generation>> {
     match backend {
         Backend::HuggingFace => parse_api_text(text),
         Backend::Ollama => parse_ollama_text(text),
diff --git a/crates/llm-ls/src/document.rs b/crates/llm-ls/src/document.rs
index 689e33b..bd06f28 100644
--- a/crates/llm-ls/src/document.rs
+++ b/crates/llm-ls/src/document.rs
@@ -1,172 +1,126 @@
 use ropey::Rope;
-use tower_lsp::jsonrpc::Result;
 use tower_lsp::lsp_types::Range;
 use tree_sitter::{InputEdit, Parser, Point, Tree};
 
+use crate::error::Result;
+use crate::get_position_idx;
 use crate::language_id::LanguageId;
-use crate::{get_position_idx, internal_error};
 
 fn get_parser(language_id: LanguageId) -> Result<Parser> {
     match language_id {
         LanguageId::Bash => {
             let mut parser = Parser::new();
-            parser
-                .set_language(tree_sitter_bash::language())
-                .map_err(internal_error)?;
+            parser.set_language(tree_sitter_bash::language())?;
             Ok(parser)
         }
         LanguageId::C => {
             let mut parser = Parser::new();
-            parser
-                .set_language(tree_sitter_c::language())
-                .map_err(internal_error)?;
+            parser.set_language(tree_sitter_c::language())?;
             Ok(parser)
         }
         LanguageId::Cpp => {
             let mut parser = Parser::new();
-            parser
-                .set_language(tree_sitter_cpp::language())
-                .map_err(internal_error)?;
+            parser.set_language(tree_sitter_cpp::language())?;
             Ok(parser)
         }
         LanguageId::CSharp => {
             let mut parser = Parser::new();
-            parser
-                .set_language(tree_sitter_c_sharp::language())
-                .map_err(internal_error)?;
+            parser.set_language(tree_sitter_c_sharp::language())?;
             Ok(parser)
         }
         LanguageId::Elixir => {
             let mut parser = Parser::new();
-            parser
-                .set_language(tree_sitter_elixir::language())
-                .map_err(internal_error)?;
+            parser.set_language(tree_sitter_elixir::language())?;
             Ok(parser)
         }
         LanguageId::Erlang => {
             let mut parser = Parser::new();
-            parser
-                .set_language(tree_sitter_erlang::language())
-                .map_err(internal_error)?;
+            parser.set_language(tree_sitter_erlang::language())?;
             Ok(parser)
         }
         LanguageId::Go => {
             let mut parser = Parser::new();
-            parser
-                .set_language(tree_sitter_go::language())
-                .map_err(internal_error)?;
+            parser.set_language(tree_sitter_go::language())?;
             Ok(parser)
         }
         LanguageId::Html => {
             let mut parser = Parser::new();
-            parser
-                .set_language(tree_sitter_html::language())
-                .map_err(internal_error)?;
+            parser.set_language(tree_sitter_html::language())?;
             Ok(parser)
         }
         LanguageId::Java => {
             let mut parser = Parser::new();
-            parser
-                .set_language(tree_sitter_java::language())
-                .map_err(internal_error)?;
+            parser.set_language(tree_sitter_java::language())?;
             Ok(parser)
         }
         LanguageId::JavaScript | LanguageId::JavaScriptReact => {
             let mut parser = Parser::new();
-            parser
-                .set_language(tree_sitter_javascript::language())
-                .map_err(internal_error)?;
+            parser.set_language(tree_sitter_javascript::language())?;
             Ok(parser)
         }
         LanguageId::Json => {
             let mut parser = Parser::new();
-            parser
-                .set_language(tree_sitter_json::language())
-                .map_err(internal_error)?;
+            parser.set_language(tree_sitter_json::language())?;
             Ok(parser)
         }
         LanguageId::Kotlin => {
             let mut parser = Parser::new();
-            parser
-                .set_language(tree_sitter_kotlin::language())
-                .map_err(internal_error)?;
+            parser.set_language(tree_sitter_kotlin::language())?;
             Ok(parser)
         }
         LanguageId::Lua => {
             let mut parser = Parser::new();
-            parser
-                .set_language(tree_sitter_lua::language())
-                .map_err(internal_error)?;
+            parser.set_language(tree_sitter_lua::language())?;
             Ok(parser)
         }
         LanguageId::Markdown => {
             let mut parser = Parser::new();
-            parser
-                .set_language(tree_sitter_md::language())
-                .map_err(internal_error)?;
+            parser.set_language(tree_sitter_md::language())?;
             Ok(parser)
         }
         LanguageId::ObjectiveC => {
             let mut parser = Parser::new();
-            parser
-                .set_language(tree_sitter_objc::language())
-                .map_err(internal_error)?;
+            parser.set_language(tree_sitter_objc::language())?;
             Ok(parser)
         }
         LanguageId::Python => {
             let mut parser = Parser::new();
-            parser
-                .set_language(tree_sitter_python::language())
-                .map_err(internal_error)?;
+            parser.set_language(tree_sitter_python::language())?;
             Ok(parser)
         }
         LanguageId::R => {
             let mut parser = Parser::new();
-            parser
-                .set_language(tree_sitter_r::language())
-                .map_err(internal_error)?;
+            parser.set_language(tree_sitter_r::language())?;
             Ok(parser)
         }
         LanguageId::Ruby => {
             let mut parser = Parser::new();
-            parser
-                .set_language(tree_sitter_ruby::language())
-                .map_err(internal_error)?;
+            parser.set_language(tree_sitter_ruby::language())?;
             Ok(parser)
         }
         LanguageId::Rust => {
             let mut parser = Parser::new();
-            parser
-                .set_language(tree_sitter_rust::language())
-                .map_err(internal_error)?;
+            parser.set_language(tree_sitter_rust::language())?;
             Ok(parser)
         }
         LanguageId::Scala => {
             let mut parser = Parser::new();
-            parser
-                .set_language(tree_sitter_scala::language())
-                .map_err(internal_error)?;
+            parser.set_language(tree_sitter_scala::language())?;
             Ok(parser)
         }
         LanguageId::Swift => {
             let mut parser = Parser::new();
-            parser
-                .set_language(tree_sitter_swift::language())
-                .map_err(internal_error)?;
+            parser.set_language(tree_sitter_swift::language())?;
             Ok(parser)
         }
         LanguageId::TypeScript => {
             let mut parser = Parser::new();
-            parser
-                .set_language(tree_sitter_typescript::language_typescript())
-                .map_err(internal_error)?;
+            parser.set_language(tree_sitter_typescript::language_typescript())?;
             Ok(parser)
         }
         LanguageId::TypeScriptReact => {
             let mut parser = Parser::new();
-            parser
-                .set_language(tree_sitter_typescript::language_tsx())
-                .map_err(internal_error)?;
+            parser.set_language(tree_sitter_typescript::language_tsx())?;
             Ok(parser)
         }
         LanguageId::Unknown => Ok(Parser::new()),
@@ -200,19 +154,13 @@ impl Document {
             range.start.line as usize,
             range.start.character as usize,
         )?;
-        let start_byte = self
-            .text
-            .try_char_to_byte(start_idx)
-            .map_err(internal_error)?;
+        let start_byte = self.text.try_char_to_byte(start_idx)?;
         let old_end_idx = get_position_idx(
             &self.text,
             range.end.line as usize,
             range.end.character as usize,
         )?;
-        let old_end_byte = self
-            .text
-            .try_char_to_byte(old_end_idx)
-            .map_err(internal_error)?;
+        let old_end_byte = self.text.try_char_to_byte(old_end_idx)?;
         let start_position = Point {
             row: range.start.line as usize,
             column: range.start.character as usize,
@@ -224,7 +172,7 @@ impl Document {
         let (new_end_idx, new_end_position) = if range.start == range.end {
             let row = range.start.line as usize;
             let column = range.start.character as usize;
-            let idx = self.text.try_line_to_char(row).map_err(internal_error)? + column;
+            let idx = self.text.try_line_to_char(row)? + column;
             let rope = Rope::from_str(text);
             let text_len = rope.len_chars();
             let end_idx = idx + text_len;
@@ -237,11 +185,10 @@ impl Document {
                 },
             )
         } else {
-            let removal_idx = self.text.try_line_to_char(range.end.line as usize).map_err(internal_error)? + (range.end.character as usize);
+            let removal_idx = self.text.try_line_to_char(range.end.line as usize)?
+                + (range.end.character as usize);
             let slice_size = removal_idx - start_idx;
-            self.text
-                .try_remove(start_idx..removal_idx)
-                .map_err(internal_error)?;
+            self.text.try_remove(start_idx..removal_idx)?;
             self.text.insert(start_idx, text);
             let rope = Rope::from_str(text);
             let text_len = rope.len_chars();
@@ -251,11 +198,8 @@ impl Document {
             } else {
                 removal_idx + character_difference as usize
             };
-            let row = self
-                .text
-                .try_char_to_line(new_end_idx)
-                .map_err(internal_error)?;
-            let line_start = self.text.try_line_to_char(row).map_err(internal_error)?;
+            let row = self.text.try_char_to_line(new_end_idx)?;
+            let line_start = self.text.try_line_to_char(row)?;
             let column = new_end_idx - line_start;
             (new_end_idx, Point { row, column })
         };
@@ -263,10 +207,7 @@ impl Document {
             let edit = InputEdit {
                 start_byte,
                 old_end_byte,
-                new_end_byte: self
-                    .text
-                    .try_char_to_byte(new_end_idx)
-                    .map_err(internal_error)?,
+                new_end_byte: self.text.try_char_to_byte(new_end_idx)?,
                 start_position,
                 old_end_position,
                 new_end_position,
diff --git a/crates/llm-ls/src/error.rs b/crates/llm-ls/src/error.rs
new file mode 100644
index 0000000..aa51588
--- /dev/null
+++ b/crates/llm-ls/src/error.rs
@@ -0,0 +1,64 @@
+use std::fmt::Display;
+
+use tower_lsp::jsonrpc::Error as LspError;
+use tracing::error;
+
+pub fn internal_error<E: Display>(err: E) -> LspError {
+    let err_msg = err.to_string();
+    error!(err_msg);
+    LspError {
+        code: tower_lsp::jsonrpc::ErrorCode::InternalError,
+        message: err_msg.into(),
+        data: None,
+    }
+}
+
+#[derive(thiserror::Error, Debug)]
+pub enum Error {
+    #[error("http error: {0}")]
+    Http(#[from] reqwest::Error),
+    #[error("io error: {0}")]
+    Io(#[from] std::io::Error),
+    #[error("inference api error: {0}")]
+    InferenceApi(crate::APIError),
+    #[error("You are attempting to parse a result in the API inference format when using the `tgi` backend")]
+    InvalidBackend,
+    #[error("invalid header value: {0}")]
+    InvalidHeaderValue(#[from] reqwest::header::InvalidHeaderValue),
+    #[error("invalid repository id")]
+    InvalidRepositoryId,
+    #[error("invalid tokenizer path")]
+    InvalidTokenizerPath,
+    #[error("ollama error: {0}")]
+    Ollama(crate::APIError),
+    #[error("openai error: {0}")]
+    OpenAI(crate::backend::OpenAIError),
+    #[error("index out of bounds: {0}")]
+    OutOfBoundIndexing(usize),
+    #[error("line out of bounds: {0}")]
+    OutOfBoundLine(usize),
+    #[error("slice out of bounds: {0}..{1}")]
+    OutOfBoundSlice(usize, usize),
+    #[error("rope error: {0}")]
+    Rope(#[from] ropey::Error),
+    #[error("serde json error: {0}")]
+    SerdeJson(#[from] serde_json::Error),
+    #[error("tgi error: {0}")]
+    Tgi(crate::APIError),
+    #[error("tree-sitter language error: {0}")]
+    TreeSitterLanguage(#[from] tree_sitter::LanguageError),
+    #[error("tokenizer error: {0}")]
+    Tokenizer(#[from] tokenizers::Error),
+    #[error("tokio join error: {0}")]
+    TokioJoin(#[from] tokio::task::JoinError),
+    #[error("unknown backend: {0}")]
+    UnknownBackend(String),
+}
+
+pub type Result<T> = std::result::Result<T, Error>;
+
+impl From<Error> for LspError {
+    fn from(err: Error) -> Self {
+        internal_error(err)
+    }
+}
diff --git a/crates/llm-ls/src/main.rs b/crates/llm-ls/src/main.rs
index fcd7d3c..c6f2c54 100644
--- a/crates/llm-ls/src/main.rs
+++ b/crates/llm-ls/src/main.rs
@@ -1,5 +1,3 @@
-use backend::{build_body, build_headers, parse_generations, Backend};
-use document::Document;
 use ropey::Rope;
 use serde::{Deserialize, Deserializer, Serialize};
 use serde_json::{Map, Value};
@@ -11,7 +9,7 @@ use std::time::{Duration, Instant};
 use tokenizers::Tokenizer;
 use tokio::io::AsyncWriteExt;
 use tokio::sync::RwLock;
-use tower_lsp::jsonrpc::{Error, Result};
+use tower_lsp::jsonrpc::Result as LspResult;
 use tower_lsp::lsp_types::*;
 use tower_lsp::{Client, LanguageServer, LspService, Server};
 use tracing::{debug, error, info, info_span, warn, Instrument};
@@ -19,8 +17,13 @@ use tracing_appender::rolling;
 use tracing_subscriber::EnvFilter;
 use uuid::Uuid;
 
+use crate::backend::{build_body, build_headers, parse_generations, Backend};
+use crate::document::Document;
+use crate::error::{internal_error, Error, Result};
+
 mod backend;
 mod document;
+mod error;
 mod language_id;
 
 const MAX_WARNING_REPEAT: Duration = Duration::from_secs(3_600);
@@ -29,10 +32,10 @@ pub const VERSION: &str = env!("CARGO_PKG_VERSION");
 const HF_INFERENCE_API_HOSTNAME: &str = "api-inference.huggingface.co";
 
 fn get_position_idx(rope: &Rope, row: usize, col: usize) -> Result<usize> {
-    Ok(rope.try_line_to_char(row).map_err(internal_error)?
+    Ok(rope.try_line_to_char(row)?
         + col.min(
             rope.get_line(row.min(rope.len_lines().saturating_sub(1)))
-                .ok_or_else(|| internal_error(format!("failed to find line at {row}")))?
+                .ok_or(Error::OutOfBoundLine(row))?
                 .len_chars()
                 .saturating_sub(1),
         ))
@@ -80,16 +83,12 @@ fn should_complete(document: &Document, position: Position) -> Result<Completion
             let mut end_offset = get_position_idx(&document.text, end.row, end.column)? - 1;
             let start_char = document
                 .text
-                .get_char(start_offset.min(document.text.len_chars() - 1))
-                .ok_or_else(|| {
-                    internal_error(format!("failed to find start char at {start_offset}"))
-                })?;
+                .get_char(start_offset.min(document.text.len_chars().saturating_sub(1)))
+                .ok_or(Error::OutOfBoundIndexing(start_offset))?;
             let end_char = document
                 .text
-                .get_char(end_offset.min(document.text.len_chars() - 1))
-                .ok_or_else(|| {
-                    internal_error(format!("failed to find end char at {end_offset}"))
-                })?;
+                .get_char(end_offset.min(document.text.len_chars().saturating_sub(1)))
+                .ok_or(Error::OutOfBoundIndexing(end_offset))?;
             if !start_char.is_whitespace() {
                 start_offset += 1;
             }
@@ -102,20 +101,13 @@ fn should_complete(document: &Document, position: Position) -> Result<Completion
             let slice = document
                 .text
                 .get_slice(start_offset..end_offset)
-                .ok_or_else(|| {
-                    internal_error(format!(
-                        "failed to find slice at {start_offset}..{end_offset}"
-                    ))
-                })?;
+                .ok_or(Error::OutOfBoundSlice(start_offset, end_offset))?;
             if slice.to_string().trim().is_empty() {
                 return Ok(CompletionType::MultiLine);
             }
         }
     }
-    let start_idx = document
-        .text
-        .try_line_to_char(row)
-        .map_err(internal_error)?;
+    let start_idx = document.text.try_line_to_char(row)?;
     // XXX: We treat the end of a document as a newline
     let next_char = document.text.get_char(start_idx + column).unwrap_or('\n');
     if next_char.is_whitespace() {
@@ -200,6 +192,12 @@ pub struct APIError {
     error: String,
 }
 
+impl std::error::Error for APIError {
+    fn description(&self) -> &str {
+        &self.error
+    }
+}
+
 impl Display for APIError {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         write!(f, "{}", self.error)
@@ -297,16 +295,6 @@ struct CompletionResult {
     completions: Vec<Completion>,
 }
 
-pub fn internal_error<E: Display>(err: E) -> Error {
-    let err_msg = err.to_string();
-    error!(err_msg);
-    Error {
-        code: tower_lsp::jsonrpc::ErrorCode::InternalError,
-        message: err_msg.into(),
-        data: None,
-    }
-}
-
 fn build_prompt(
     pos: Position,
     text: &Rope,
@@ -335,10 +323,7 @@ fn build_prompt(
             if let Some(before_line) = before_line {
                 let before_line = before_line.to_string();
                 let tokens = if let Some(tokenizer) = tokenizer.clone() {
-                    tokenizer
-                        .encode(before_line.clone(), false)
-                        .map_err(internal_error)?
-                        .len()
+                    tokenizer.encode(before_line.clone(), false)?.len()
                 } else {
                     before_line.len()
                 };
@@ -351,10 +336,7 @@ fn build_prompt(
             if let Some(after_line) = after_line {
                 let after_line = after_line.to_string();
                 let tokens = if let Some(tokenizer) = tokenizer.clone() {
-                    tokenizer
-                        .encode(after_line.clone(), false)
-                        .map_err(internal_error)?
-                        .len()
+                    tokenizer.encode(after_line.clone(), false)?.len()
                 } else {
                     after_line.len()
                 };
@@ -390,10 +372,7 @@ fn build_prompt(
             }
             let line = line.to_string();
             let tokens = if let Some(tokenizer) = tokenizer.clone() {
-                tokenizer
-                    .encode(line.clone(), false)
-                    .map_err(internal_error)?
-                    .len()
+                tokenizer.encode(line.clone(), false)?.len()
             } else {
                 line.len()
             };
@@ -424,22 +403,18 @@ async fn request_completion(
         .json(&json)
         .headers(headers)
         .send()
-        .await
-        .map_err(internal_error)?;
+        .await?;
 
     let model = &params.model;
-    let generations = parse_generations(
-        &params.backend,
-        res.text().await.map_err(internal_error)?.as_str(),
-    );
+    let generations = parse_generations(&params.backend, res.text().await?.as_str())?;
     let time = t.elapsed().as_millis();
     info!(
         model,
         compute_generations_ms = time,
-        generations = serde_json::to_string(&generations).map_err(internal_error)?,
+        generations = serde_json::to_string(&generations)?,
         "{model} computed generations in {time} ms"
     );
-    generations
+    Ok(generations)
 }
 
 fn format_generations(
@@ -482,22 +457,19 @@ async fn download_tokenizer_file(
     if to.as_ref().exists() {
         return Ok(());
     }
-    tokio::fs::create_dir_all(
-        to.as_ref()
-            .parent()
-            .ok_or_else(|| internal_error("invalid tokenizer path"))?,
-    )
-    .await
-    .map_err(internal_error)?;
+    tokio::fs::create_dir_all(to.as_ref().parent().ok_or(Error::InvalidTokenizerPath)?).await?;
     let headers = build_headers(&Backend::HuggingFace, api_token, ide)?;
     let mut file = tokio::fs::OpenOptions::new()
         .write(true)
         .create(true)
         .open(to)
-        .await
-        .map_err(internal_error)?;
+        .await?;
     let http_client = http_client.clone();
     let url = url.to_owned();
+    // TODO:
+    // - create oneshot channel to send result of tokenizer download to display error message
+    // to user?
+    // - retry logic?
     tokio::spawn(async move {
         let res = match http_client.get(url).headers(headers).send().await {
             Ok(res) => res,
@@ -527,8 +499,7 @@ async fn download_tokenizer_file(
             }
         };
     })
-    .await
-    .map_err(internal_error)?;
+    .await?;
     Ok(())
 }
 
@@ -556,7 +527,14 @@ async fn get_tokenizer(
                 repository,
                 api_token,
             } => {
-                let path = cache_dir.as_ref().join(repository).join("tokenizer.json");
+                let (org, repo) = repository
+                    .split_once('/')
+                    .ok_or(Error::InvalidRepositoryId)?;
+                let path = cache_dir
+                    .as_ref()
+                    .join(org)
+                    .join(repo)
+                    .join("tokenizer.json");
                 let url =
                     format!("https://huggingface.co/{repository}/resolve/main/tokenizer.json");
                 download_tokenizer_file(http_client, &url, api_token.as_ref(), &path, ide).await?;
@@ -597,7 +575,7 @@ fn build_url(model: &str) -> String {
 }
 
 impl LlmService {
-    async fn get_completions(&self, params: CompletionParams) -> Result<CompletionResult> {
+    async fn get_completions(&self, params: CompletionParams) -> LspResult<CompletionResult> {
         let request_id = Uuid::new_v4();
         let span = info_span!("completion_request", %request_id);
         async move {
@@ -669,7 +647,7 @@ impl LlmService {
         }.instrument(span).await
     }
 
-    async fn accept_completion(&self, accepted: AcceptedCompletion) -> Result<()> {
+    async fn accept_completion(&self, accepted: AcceptedCompletion) -> LspResult<()> {
         info!(
             request_id = %accepted.request_id,
             accepted_position = accepted.accepted_completion,
@@ -679,7 +657,7 @@ impl LlmService {
         Ok(())
     }
 
-    async fn reject_completion(&self, rejected: RejectedCompletion) -> Result<()> {
+    async fn reject_completion(&self, rejected: RejectedCompletion) -> LspResult<()> {
         info!(
             request_id = %rejected.request_id,
             shown_completions = serde_json::to_string(&rejected.shown_completions).map_err(internal_error)?,
@@ -691,7 +669,7 @@ impl LlmService {
 
 #[tower_lsp::async_trait]
 impl LanguageServer for LlmService {
-    async fn initialize(&self, params: InitializeParams) -> Result<InitializeResult> {
+    async fn initialize(&self, params: InitializeParams) -> LspResult<InitializeResult> {
         *self.workspace_folders.write().await = params.workspace_folders;
         Ok(InitializeResult {
             server_info: Some(ServerInfo {
@@ -743,7 +721,7 @@ impl LanguageServer for LlmService {
         }
 
         // ignore the output scheme
-        if uri.starts_with("output:") {
+        if params.text_document.uri.scheme() == "output" {
             return;
         }
 
@@ -786,7 +764,7 @@ impl LanguageServer for LlmService {
         info!("{uri} closed");
     }
 
-    async fn shutdown(&self) -> Result<()> {
+    async fn shutdown(&self) -> LspResult<()> {
         debug!("shutdown");
         Ok(())
     }