error.bufferedData is missing in 7.0.0 (except on maxBuffer error)

[ehmicky]

Before 7.0.0, when the stream errored, the currently buffered data would be available as error.bufferedData. Since 7.0.0, this is not the case anymore, except when maxBuffer is hit.

Re-adding this feature should be fairly simple and non-breaking, since the data is already being buffered in the code, i.e. we'd only need to add a try/catch handler that sets error.bufferedData = getBufferedValue(). I'm happy to submit a PR if that sounds good.

This issue is preventing Execa from upgrading get-stream from v6 to v7. This is because Execa sets error.stdout, error.stderr and error.all using the logic described above.

https://github.com/sindresorhus/execa/blob/65992b418816b965d2e3f89b44d3c259ecd0c99a/lib/stream.js#L75-L89

[sindresorhus]

Sounds good. It was just an oversight. PR welcome :)

[ehmicky]

Done at #63.