[GitHub] jthomas opened a new issue #63: Thrown errors from async function missing details

[GitBox <gi...@apache.org>]

jthomas opened a new issue #63: Thrown errors from async function missing details
URL: https://github.com/apache/incubator-openwhisk-runtime-nodejs/issues/63
 
 
   ## Environment details:
   
   IBM Cloud Functions 
   
   ## Steps to reproduce the issue:
   
   Create a function using the Node.js 8 runtime with this code snippet.
   
   ```js
   const main = () => {
       return a.b.c
   }
   ```
   
   Invoking this action, the following activation response is returned.
   ```json
   {
     "error": "An error has occurred: ReferenceError: a is not defined"
   }
   ```
   Stack trace is included in the logs.
   
   ```
   "2018-06-19T16:29:11.783438495Z stderr: ReferenceError: a is not defined"
   "2018-06-19T16:29:11.783496031Z stderr: at NodeActionRunner.main [as userScriptMain] (eval at NodeActionRunner.init (/nodejsAction/runner.js:76:45), <anonymous>:13:5)"
   "2018-06-19T16:29:11.783515019Z stderr: at /nodejsAction/runner.js:95:45"
   ...
   ```
   
   Change the action code to the following source.
   
   ```js
   const main = async () => {
       return a.b.c
   }
   ```
   
   Invoking the updated action, the following activation response is returned.
   
   ```json
   {
     "error": {}
   }
   ```
   
   Nothing is logged to stdout or stderr for this activation.
   
   This also affect all error handling for async functions, where errors are thrown to signal errors from user-land code.
   
   ### cause 
   
   Looking at the code, when an error is thrown from async functions, it ends up in `catch` callback handler @ https://github.com/apache/incubator-openwhisk-runtime-nodejs/blob/master/core/nodejsActionBase/runner.js#L107-L117
   
   It [returns the Error object](https://github.com/apache/incubator-openwhisk-runtime-nodejs/blob/master/core/nodejsActionBase/runner.js#L115) thrown from the async function as the child property of the `error` key in the normal response body.
   
   Error objects serialise to an empty object when converting to JSON, which explains the empty object returned in the activation response.
   
   ```
   > JSON.stringify(new Error('hello'))
   '{}'
   ```
   
   ### fix
   
   Async error should mirror response & log values from normal errors, return `err.message` in result and log stack track. 
   
   ### next steps
   **If people agree with this diagnosis and the suggested resolution, I can try to submit a PR to resolve this?**

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