I host my own gitlab-ce instance in docker which works well. I mainly needed a web UI for git and I track issues with it. I think there are boards or at least free plugins for the community version, but I do not use them.
You can version your documentation in .md files too.
Not sure if it can substitute Jira for you, but you mentioned Bugzilla and I like gitlab a lot more.
Just make sure to update the container regularly, you can't make big version jumps without the intermediate updates.
I think you can combine it with OpenProject if you need more project planning.
Usually a sign of multiprocessing/multithreading going wrong, e.g. accessing the same resource without proper locks like opening the same logfile in different processes and trying to write simultaneously.
Those errors can be triggered just by reformating the code (or obfuscating in this case), thus changing the runtime behaviour slightly.
Hard to find, especially since they're dependent on the speed/workload of the machine running the code.