Include error codes

index.js

@@ -27,13 +27,13 @@ module.exports = function (protocols) {
 				: null;
 
 			if (parsedProtocol == null) {
-				return new ValidationError("Must be a valid URL");
+				return new ValidationError("Must be a valid URL", { code: "validatem.is-url.invalid-url" });
 			} else if (protocolSet != null && !protocolSet.has(parsedProtocol.toLowerCase())) {
 				let validProtocolList = protocols
 					.map((protocol) => protocol.toUpperCase())
 					.join(", ");
 
-				return new ValidationError(`Must be a URL with one of the following protocols: ${validProtocolList} - but got ${parsedProtocol.toUpperCase()} instead`);
+				return new ValidationError(`Must be a URL with one of the following protocols: ${validProtocolList} - but got ${parsedProtocol.toUpperCase()} instead`, { code: "validatem.is-url.wrong-protocol" });
 			} else {
 				return parsed;
 			}