Well, one of the consequences of me blowing up my computer for almost no reason is that my game didn't work, possibly initially because symlinks cloned from git don't really work, but after that because Godot, once it's convinced a class is duplicated across files, continues to believe that, even after you've fixed things on the filesystem.
So, people end up doing
things like this:
I sometimes get the same parse error after renaming or moving script files. It feels like it doesn’t happen that often anymore in 4.2.2 but whenever it happens, I fix it like this:
Change class_name to some temporary class_name (“MyClass” → “MyClass1”)
Save the script
Change class_name back to the original name (“MyClass1” → “MyClass”)
Save the script
Restart Godot
That is nuts. My solution is to delete the .godot directory, then reload the project. Which is also something I resent doing, but is way less work than renaming every class twice.