I've been getting this crash (https://i.imgur.com/CW7Sb2X.png) whenever a research completes while trainsaver is active. It does say the crash is caused by GUIUnifier (and it also mentions Factory Planner in the crash), so this may not be your fault at all/not fixable on your end, but figured I should post here too just incase, as the only time this ever seems to occur to me is when trainsaver is active (not just enabled, the crash only occurs when both the trainsaver is ACTIVE aka looking at a train, when a research completes). Maybe it has something to do with how you set up the UI-hiding anti-burn-in feature a few months ago?

Dang it. I was worried something like this would come up. You are right that although the other mods are causing the error, the root cause is trainsaver modifying their gui visibility, and those mods assuming that that would never happen.
I’ll need to think about a solution for this one. I had refrained from adding the gui hiding feature for quite a long time for fear of this exact issue, but I did finally add it because there were quite a few mods not hiding their gui during cutscenes and they didn’t seem likely to publish an update anytime soon.
Since this is causing a crash, I may need to just remove the gui hiding feature altogether until a good solution appears.
Thanks for the report, I appreciate it a lot!

Perhaps make the GUI hiding feature an opt-in toggle?