docs: end(cb) cb can be invoked with error

[ronag]

callback Optional callback for when the stream is finished

https://nodejs.org/dist/latest-v13.x/docs/api/stream.html#stream_writable_end_chunk_encoding_callback

Should be updated to indicate that the callback can also be invoked with error.

[ronag]

Waiting for consensus on the callback discussion #31179 (comment)