improv(commons): add number key type to JSONObject type

The change introduced in this PR allows to narrow the type of JSON objects using numbers as key. JSON allows only string types as keys, however JavaScript coerces the value to a string even when a number is passed.

packages/commons/src/types/utils.ts

@@ -53,7 +53,7 @@ export { isRecord, isString, isTruthy, isNullOrUndefined };
 
 type JSONPrimitive = string | number | boolean | null | undefined;
 type JSONValue = JSONPrimitive | JSONObject | JSONArray;
-type JSONObject = { [key: string]: JSONValue };
+type JSONObject = { [key: number | string]: JSONValue };
 type JSONArray = Array<JSONValue>;
 
 export type { JSONPrimitive, JSONValue, JSONObject, JSONArray };