add Errors.php

classes/errors.php

+<?php
+class Errors {
+	const E_SUCCESS = "E_SUCCESS";
+	const E_UNAUTHORIZED = "E_UNAUTHORIZED";
+	const E_UNKNOWN_METHOD = "E_UNKNOWN_METHOD";
+	const E_UNKNOWN_PLUGIN = "E_UNKNOWN_PLUGIN";
+	const E_SCHEMA_MISMATCH = "E_SCHEMA_MISMATCH";
+
+	static function to_json(string $code) {
+		return json_encode(["error" => ["code" => $code]]);
+	}
+}