Add error detail to catch-all HTTP response (#1854)

(cherry picked from commit c51c26f)

# Conflicts:
#	CHANGELOG.next.asciidoc

CHANGELOG.next.asciidoc

@@ -1,3 +1,20 @@
 ==== Bugfixes
 
 - Return a better error on enrolling and the Elasticsearch version is incompatible. {pull}1211[1211]
+<<<<<<< HEAD
+=======
+- Give a grace period when starting the unenroll monitor. {issue}1500[1500]
+- Fixes a race condition between the unenroller goroutine and the main goroutine for the coordinator monitor. {issues}1738[1738]
+- Remove events from agent checkin body. {issue}1774[1774]
+- Add error detail to catch-all HTTP error response. {pull}1854[1854]
+
+==== New Features
+
+- Fleet server now supports Logstash type outputs for managed agents. {pull}1188[1188]
+- Use the darwin-aarch64 as the suffix for Darwin Arm64 release {pull}1267[1267]
+- Allow Elastic Agent to provide tags at enrollment time to identify them. {pull}1350[1350]
+- Add start_time and minimum_execution_duration to actions to allow fleet-server to schedule agent actions. {pull}1381[1381]
+- Fleet Server now allows setting global labels on APM instrumentation. {pull}1649[1649]
+- Fleet Server now allows setting transaction sample rate on APM instrumentation {pull}1681[1681]
+- Log redacted config when config updates. {issue}1626[1626] {pull}1668[1668]
+>>>>>>> c51c26f (Add error detail to catch-all HTTP response (#1854))

cmd/fleet/error.go

@@ -148,6 +148,7 @@ func NewErrorResp(err error) errResp {
 	return errResp{
 		StatusCode: http.StatusBadRequest,
 		Error:      "BadRequest",
+		Message:    err.Error(),
 		Level:      zerolog.InfoLevel,
 	}
 }