fix: JSON parsing with trailing commas enabled (#37)

* 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.

* refactor: JSON parse error message formatting.

- Refactored the JSON parse error messages in `constructJsonParseErrorMsg` util function to include the original error name, as well as the formatted name, just to ensure the errors have a proper error code for debugging.

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);
@@ -78,19 +79,18 @@ function constructJsonParseErrorMsg(filepath: string, fileContent: string, jsonE
 	return jsonErrors
 		.map((err, i) => {
 			// Get the error name from the numeric error code.
-			// The name is PascalCased, so we need to format it by adding spaces
+			const errorName = jsonc.printParseErrorCode(err.error);
+
+			// The error name is PascalCased, so we need to format it by adding spaces
 			// before capital letters for readability.
-			const errorName = jsonc
-				.printParseErrorCode(err.error)
-				.replace(/([A-Z])/g, " $1")
-				.trim();
+			const errorNameFormatted = errorName.replace(/([A-Z])/g, " $1").trim();
 
 			// Calculate line and column numbers from the error offset.
 			const lineNumber = fileContent.substring(0, err.offset).split("\n").length;
 			const columnNumber = err.offset - fileContent.lastIndexOf("\n", err.offset - 1);
 
 			// Return the formatted error message.
-			return `\tError ${i + 1} - ${errorName} at "${filepath}:${lineNumber}:${columnNumber}"\n`;
+			return `\tError ${i + 1} [${errorName}] - ${errorNameFormatted} at "${filepath}:${lineNumber}:${columnNumber}"\n`;
 		})
 		.join("\n");
 }