Queue::write_buffer_with() should precisely document its Option return

[kpreid]

Queue::write_buffer_with() returns Option<QueueWriteBufferView<'a>>. Looking at the source, the Option is None on some error conditions. This is unusual, and not clearly documented. I presume the reason write_buffer_with() works this way is that if any error occurs, it can't return a functional QueueWriteBufferView. But in that case, the question remains: is the error also being reported to the error scope? If yes, then callers can just use if let Some(view) = write_buffer_with() { ... do stuff ... }; if no, then they may need to do additional handling.

The return type of write_buffer_with() should be clearly documented so that it can be handled appropriately.