allowed throwing of built in errors from the error handler

Author: sdangol

packages/event-handler/src/rest/Router.ts

@@ -331,6 +331,12 @@ class Router {
           headers: { 'Content-Type': 'application/json' },
         });
       } catch (handlerError) {
+        if (handlerError instanceof NotFoundError) {
+          return await this.handleError(handlerError, options);
+        }
+        if (handlerError instanceof MethodNotAllowedError) {
+          return await this.handleError(handlerError, options);
+        }
         return this.#defaultErrorHandler(handlerError as Error);
       }
     }

packages/event-handler/src/types/rest.ts

@@ -12,11 +12,17 @@ import type { Route } from '../rest/Route.js';
 import type { Router } from '../rest/Router.js';
 import type { ResolveOptions } from './common.js';
 
-type ErrorResponse = {
-  statusCode: HttpStatusCode;
-  error: string;
-  message: string;
-};
+type ErrorResponse =
+  | {
+      statusCode: HttpStatusCode;
+      error: string;
+      message?: string;
+    }
+  | {
+      statusCode: HttpStatusCode;
+      error?: string;
+      message: string;
+    };
 
 type RequestContext = {
   req: Request;

packages/event-handler/tests/unit/rest/Router/error-handling.test.ts

@@ -5,6 +5,7 @@ import {
   HttpErrorCodes,
   InternalServerError,
   MethodNotAllowedError,
+  NotFoundError,
   Router,
 } from '../../../../src/rest/index.js';
 import { createTestEvent } from '../helpers.js';
@@ -429,4 +430,32 @@ describe('Class: Router - Error Handling', () => {
       isBase64Encoded: false,
     });
   });
+
+  it('handles throwing a built in error from the error handler', async () => {
+    // Prepare
+    const app = new Router();
+
+    app.errorHandler(BadRequestError, async () => {
+      throw new NotFoundError('This error is thrown from the error handler');
+    });
+
+    app.get('/test', () => {
+      throw new BadRequestError('test error');
+    });
+
+    // Act
+    const result = await app.resolve(createTestEvent('/test', 'GET'), context);
+
+    // Assess
+    expect(result).toEqual({
+      statusCode: HttpErrorCodes.NOT_FOUND,
+      body: JSON.stringify({
+        statusCode: HttpErrorCodes.NOT_FOUND,
+        error: 'NotFoundError',
+        message: 'This error is thrown from the error handler',
+      }),
+      headers: { 'content-type': 'application/json' },
+      isBase64Encoded: false,
+    });
+  });
 });