There is a "child of" or "copy transforms" constraint on an object in your scene which doesn't have a target. The constraint is broken, does nothing, and can be removed.

I'll avoid this error in the next version of the Source Tools.

There is invalid text somewhere in the file. Is it a binary file or text?

This object is created on import to help you diagnose VTA mismatches. You can delete it if you aren't using it.

You need to tick the box in the outliner next to the collection. "YellowBear" is excluded in the file that you uploaded.

These messages are because the collection that contains the object is excluded from the scene. I will change the exporter so that it doesn't try to export such objects.

If you can make the most recent version of Blender crash too, then I'll take a closer look.

The script's behaviour changed and exposed a bug in that version of Blender. It's not doing anything wrong.

That file isn't public.

Please report this to Blender. You can also upgrade...

It's a bug in older versions. You can update manually.