fix: JSON parsing with trailing commas enabled in readJsonFile.

Fixes #36.

During parsing of JSON files, the parser will throw an `ValueExpected` error when it reaches a comma and unexpectedly encounters a closing bracket straight after. Trailing commas are disabled in the parser by default as it's not standard in JSON or JSONC. So it expects some kind of value after all commas. Luckily, we can enable trailing commas...

- Fixed `ValueExpected` JSON parse error for trailing commas by enabling the `allowTrailingComma` parse option in `readJsonFile` util function. This is especially useful when parsing language config files, when the contributing extension has auto-formatting enabled for trailing commas.

Author: yCodeTech

src/utils.ts

@@ -38,7 +38,8 @@ export function readJsonFile<T extends JsonValue = JsonObject>(filepath: string,
 		.toString()
 		.replace(/^\uFEFF/, ""); // Remove BOM if present.
 
-	const jsonContents = jsonc.parse(fileContent, jsonErrors, {allowEmptyContent: true}) ?? {};
+	// Parse the JSON content using jsonc-parser, allowing empty content and trailing commas.
+	const jsonContents = jsonc.parse(fileContent, jsonErrors, {allowEmptyContent: true, allowTrailingComma: true}) ?? {};
 
 	if (jsonErrors.length > 0) {
 		const errorMessages = constructJsonParseErrorMsg(filepath, fileContent, jsonErrors);