Improved error message

Co-authored-by: Simen Bekkhus <[email protected]>

lib/util.js

@@ -54,7 +54,7 @@ exports.getLabels = function (labelNames, args) {
 
 	if (labelNames.length !== args.length) {
 		throw new Error(
-			`Invalid number of arguments: "${args.join()}" for label names: "${labelNames.join()}".`,
+			`Invalid number of arguments (${args.length}): "${args.join(', ')}" for label names (${labelNames.length}): "${labelNames.join(', ')}".`,
 		);
 	}