fix the wrong response

error.go

@@ -390,18 +390,18 @@ func ErrorController(c ControllerInterface) *App {
 // show error string as simple text message.
 // if error string is empty, show 503 or 500 error as default.
 func exception(errCode string, ctx *context.Context) {
-	for _, ec := range []string{errCode, "503", "500"} {
 	code, _ := strconv.Atoi(errCode)
 	if code == 0 {
 		code = 503
 	}
+	for _, ec := range []string{errCode, "503", "500"} {
 		if h, ok := ErrorMaps[ec]; ok {
 			executeError(h, ctx, code)
 			return
 		}
 	}
 	//if 50x error has been removed from errorMap
-	ctx.ResponseWriter.WriteHeader(503)
+	ctx.ResponseWriter.WriteHeader(code)
 	ctx.WriteString(errCode)
 }