fix: enhance exception handling documentation and add example resolver

Author: arnabrahman

docs/features/event-handler/appsync-graphql.md

@@ -150,16 +150,24 @@ You can access the original Lambda event or context for additional information.
 
 ### Exception Handling
 
-You can use the **`exceptionHandler`** method with any exception. This allows you to handle common errors outside your resolver and return a custom response.
+You can use the **`exceptionHandler`** method to handle any exception. This allows you to handle common errors outside your resolver and return a custom response.
 
-You can use a VTL response mapping template to detect these custom responses and forward them to the client gracefully.
+The **`exceptionHandler`** method also supports passing an array of exceptions that you wish to handle with a single handler.
+
+You can use an AppSync JavaScript resolver or a VTL response mapping template to detect these custom responses and forward them to the client gracefully.
 
 === "Exception Handling"
 
     ```typescript hl_lines="11-18 21-23"
     --8<-- "examples/snippets/event-handler/appsync-graphql/exceptionHandling.ts"
     ```
 
+=== "APPSYNC JS Resolver"
+
+    ```js hl_lines="11-13"
+    --8<-- "examples/snippets/event-handler/appsync-graphql/exceptionHandlingResolver.js"
+    ```
+
 === "VTL Response Mapping Template"
 
     ```velocity hl_lines="1-3"

examples/snippets/event-handler/appsync-graphql/exceptionHandlingResolver.js

@@ -0,0 +1,15 @@
+import { util } from '@aws-appsync/utils';
+
+export function request(ctx) {
+  return {
+    operation: 'Invoke',
+    payload: ctx,
+  };
+}
+
+export function response(ctx) {
+  if (ctx.result.error) {
+    return util.error(ctx.result.error.message, ctx.result.error.type);
+  }
+  return ctx.result;
+}