diff --git a/package.json b/package.json
index 3657c80..0ca46f9 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
    "name": "@hibas123/jrpcgen",
-   "version": "1.2.5",
+   "version": "1.2.6",
    "main": "lib/index.js",
    "license": "MIT",
    "packageManager": "yarn@3.1.1",
diff --git a/templates/ts_base.ts b/templates/ts_base.ts
index 7c27aa2..b3b9e3f 100644
--- a/templates/ts_base.ts
+++ b/templates/ts_base.ts
@@ -1,14 +1,24 @@
+import { isGeneratorFunction } from "util/types";
+
+function form_verficiation_error_message(type?: string, field?: string) {
+   let msg = "Parameter verification failed! ";
+   if (type && field) {
+      msg += `At ${type}.${field}! `;
+   } else if (type) {
+      msg += `At type ${type}! `;
+   } else if (field) {
+      msg += `At field ${field}! `;
+   }
+   return msg;
+}
+
 export class VerificationError extends Error {
    constructor(
       public readonly type?: string,
       public readonly field?: string,
       public readonly value?: any
    ) {
-      super(
-         "Parameter verification failed! " +
-            (type ? "Expected " + type + "! " : "") +
-            (field ? "At: " + field + "! " : "")
-      );
+      super(form_verficiation_error_message(type, field));
    }
 }
 
@@ -33,4 +43,4 @@ export function apply_boolean(data: any) {
    return Boolean(data);
 }
 
-export function apply_void(data: any) {}
+export function apply_void(data: any) { }