Improve stream error handling

[ehmicky]

When maxBuffer is reached, the rejected error has a different shape than usual:

{
	"name": "MaxBufferError",
	"bufferedData": "...",
	"stream": "stdout"
}

Shouldn't it have the same shape? For example:

// No `code`, `exitCode`, `exitCodeName`, `signal`
{
	// If available
	stdout,
	stderr, 
	all,

	// This indicates a stream error
	stream: "stdout",
	// This indicates a stream error due to `maxBuffer`
	maxBuffer: true|false,

	failed: true,
	timedOut: false,
	isCanceled: false,
	
	command: "...",
}

stdout, stderr and all could either:
a) be present only if the whole stream finished before the error
b) show the partially bufferedData

The error message could be made more descriptive as well.

I can submit a PR if you think that's a good idea.

[sindresorhus]

Yes. Good catch. That's really just an oversight. PR welcome.

b) show the partially bufferedData

👍 Just make sure to document this behavior in the readme/TS.