TypeError: Cannot read property 'toString' of undefined

[ps06756]

Node version:

4.4.4

ShellJS version (the most recent version/Github branch you see the bug on):

0.7.0

Operating system:

OSX 10.11.5 El Captain

Description of the bug:

Typerror while using shell.exec

Example ShellJS command to reproduce the error:

java -jar CMDRunner.jar --tool Reporter --generate-png test.png --input-jtl results.jtl --plugin-type ResponseTimesOverTime --width 800 --height 600

I cannot find a simple command which reproduces the above issue, I am attaching a screenshot of the error message I am getting.

[ariporad]

Hmm... This is really quite strange...

@ps06756, would it be possible for you to share the .jar file with us? (Or does this happen with other .jar's?) I'm somewhat at a loss for what's happening.

[ps06756]

I am using the following jar.
CMDRunner.jar.zip

If I run the same command, from a terminal then the command runs without any problem.

[nfischer]

@ariporad Are you still looking into this?

[nfischer]

I saw a related error on an OS X Travis worker. Here's a screenshot, in case the build restarts and wipes out this log:

[ariporad]

@nfischer: I think that's related to shjs, which is in need of some help, ref #497.

[ariporad]

@ps06756: Sorry for the delay, I've been really busy recently.

Could you try this with the #471 branch? I've added some debugging stuff which should hopefully be helpful.

[nfischer]

@nfischer: I think that's related to shjs, which is in need of some help, ref #497.

Yes, that's the PR in which the error occurred. I posted it, not to suggest that it's occurring on master branch, but as an example of the error to help with debugging this issue, since neither you nor I have seen the bug pop up in our usage of ShellJS.

[ariporad]

What?

[eisenbergrobin]

I'm getting this issue pretty frequently when running a development server with webpack:

  [491] ./~/moment/locale/lt.js/private/var/folders/ll/pd5zlkb138ldyyq6mzz9zd8h0000gn/T/shelljs_b5a18701642053f3a4d2:4
  fs.writeFileSync("/var/folders/ll/pd5zlkb138ldyyq6mzz9zd8h0000gn/T/shelljs_0cf1d4941d3414207791", err ? err.code.toString() : '0');
                                                                                                                  ^

TypeError: Cannot read property 'toString' of undefined
    at /private/var/folders/ll/pd5zlkb138ldyyq6mzz9zd8h0000gn/T/shelljs_b5a18701642053f3a4d2:4:115
    at ChildProcess.exithandler (child_process.js:220:5)
    at emitTwo (events.js:87:13)
    at ChildProcess.emit (events.js:172:7)
    at maybeClose (internal/child_process.js:821:16)
    at Process.ChildProcess._handle.onexit (internal/child_process.js:211:5)
exec: internal error
/script/lib/common.js:40
  if (res.code !== 0) {
         ^

TypeError: Cannot read property 'code' of null

On MacOS X 10.11.6 (El Capitan), Node 4.3.2.

I reproduce this at least twice a day. @ariporad Would you like me to try something to help out with debugging? I can run the #470 branch if you need.

[ariporad]

@eisenbergrobin: Sure, if you wouldn't mind trying out the debug/471 branch, that would rock. I think it should be a bit more verbose.

[eisenbergrobin]

@ariporad:

Tried putting your debug/471 branch, unfortunately it seems the code is not valid:

You are missing a trailing double-quote and comma here and a comma here.

I fixed it locally, but you might want to fix it on your branch :)

So I'm now running this, I'll get back to you if I get any interesting debug information.

[ariporad]

@eisenbergrobin: Continually proving my geinousnessness. 😄 Fixed.

[eisenbergrobin]

@ariporad:

Reproduced it. Here is the extra information from your console.log:

[Error: stdout maxBuffer exceeded] cmd: '/bin/sh -c npm run start'

So it seems I am exceeding the max stdout output buffer...
I've reduced logging verbosity on my webpack-dev-middleware and that should mitigate the problem enough for me not to see it (fingers crossed).

Thanks for the help :)

[eisenbergrobin]

For those of you having the same issue when running a development server under webpack-dev-middleware, this occurs because the command is outputting (after a while) more than what the buffer can handle in a single command.

I fixed it by making my middleware less verbose when rebuilding:

app.use(require('webpack-dev-middleware')(compiler, {
  noInfo: true,
  stats: {
    colors: true,
    assets: false,
    version: false,
    hash: false,
    timings: false,
    chunks: false,
    chunkModules: false,
  },
}));

That means less lines are printed, and I still get information on whether the build was successful and what went wrong.

[ariporad]

@eisenbergrobin: Have you tried changing the maxBuffer?

[eisenbergrobin]

@ariporad: Continually proving my geniusness 😄 . I had no idea I could pass options from node::child_process to shelljs::exec to handle this.

I haven't reproduced the issue since the fix described above (since my webpack output was way too verbose anyways), but I increased the buffer size in any case:

const options = {
    ...opts,
    maxBuffer: 1024 * 1000, // Increase maxBuffer on node exec for long-running 'watch' commands with a lot of output to stdout
  };
return shell.exec(cmd, options);

Thanks for your help :)

[nfischer]

Sounds like the root cause of this issue has been solved, so I'll go ahead and close this. Please ping this thread if the toString issues occur for some other reason.