Ever since zls has had a way to load packages from a build.zig, there have always been weird, silent bugs that have prevented some (or all in some cases) users from having any package completions. Most of the silence is due to the fact that when zls exec's zig to run the build runner, it only returns an error indicating failure.

It would be helpful if zls also kept track of stderr and would log it before erroring out to the caller.