Log worker stdout/err buffers

Some functions produce a lot of stdout/err which ends up filling the buffer and causing issues as we never read it. We should likely update the worker subprocess to route stdout/err to DEVNULL.

Start by locating the worker subprocess creation and inspect how its stdout and stderr are currently handled. Route both streams to DEVNULL, then verify that functions producing substantial output no longer fill an unread buffer.

Written by the indexing model from the issue text.