fix(lambda-nodejs): handler filename missing from error message (aws#…

…14564)


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*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/@aws-cdk/aws-lambda-nodejs/lib/function.ts

@@ -155,7 +155,7 @@ function findEntry(id: string, entry?: string): string {
     return jsHandlerFile;
   }
 
-  throw new Error('Cannot find entry file.');
+  throw new Error(`Cannot find handler file ${tsHandlerFile} or ${jsHandlerFile}`);
 }
 
 /**

packages/@aws-cdk/aws-lambda-nodejs/test/function.test.ts

@@ -98,7 +98,7 @@ test('throws when entry does not exist', () => {
 });
 
 test('throws when entry cannot be automatically found', () => {
-  expect(() => new NodejsFunction(stack, 'Fn')).toThrow(/Cannot find entry file./);
+  expect(() => new NodejsFunction(stack, 'Fn')).toThrow(/Cannot find handler file .*function.test.Fn.ts or .*function.test.Fn.js/);
 });
 
 test('throws with the wrong runtime family', () => {