Thanks a lot, it's OK to post bugs here.
This error should not happen because flatboat tries to load that file, I capture that very lately. I may have introduced that bug with outline or annotation support.
Edit: Until I fix this (with the next release), you have to remove the settings file (/home/user/.config/flatboat/flatboat.conf), if you encounter this bug. Of course, the histories (recent documents and each in-document history) are lost in this case.
Edit2: Can you provide more details? I can't reproduce that bug, I just see the golden background, you should see after a fresh install.
Edit3: This only happens in column mode: the QList holding the columns is empty and I didn't check that in one place.