print output of failed prepublish scripts #441

[iliazeus]

This PR fixes #441

[iliazeus]

https://github.com/iliazeus/vscode-vsce/commit/c21dcad6ca46bac1bd5b88f75e1d90abbc80571b wasn't good enough, because it caused stderr to be doubled

[joaomoreno]

Maybe also print stderr.

Suggested change

	// in case of error, stderr gets written by a top-level exception handler
	if (error !== undefined) throw error;
	process.stderr.write(stderr);
	process.stderr.write(stderr);
	// in case of error, stderr gets written by a top-level exception handler
	if (error) {
	throw error;
	}

[iliazeus]

Well, I don't know for sure why that happens yet, but (as I said in the comment) stderr gets printed anyway when the exception is thrown and caught somewhere on top. That is, if we print it here explicitly, it gets printed twice.

My guess is that the message of an Error that gets thrown by exec() is set to contain the stderr of a child process. Or maybe toString() of this Error gives us that.

[iliazeus]

Welcome to Node.js v13.12.0.
Type ".help" for more information.
> const cp = require('child_process')
undefined
> let error
undefined
> void cp.exec('>&2 echo this gets printed to stderr && exit 1', e => error = e)
undefined
> error.toString()
'Error: Command failed: >&2 echo this gets printed to stderr && exit 1\n' +
  'this gets printed to stderr \r\n'
> error.message
'Command failed: >&2 echo this gets printed to stderr && exit 1\n' +
  'this gets printed to stderr \r\n'

[joaomoreno]

Thanks! Ended up replacing exec with spawn, which gives us the ability to inherit stdio, keep order of messages and clears the double error output issue.