Closing editors in workbench raises exception about pyface HOT 3 CLOSED

Simplest thing to do is to guard each with if self.control is not None:

from pyface.

Each line individually? There is a statement like that around the full body of the function, but if fails on the third line:

        if self.control is not None:
            self.control.hide()
            self.control.close()
            self.control.deleteLater()
            self.control = None

from pyface.

Ah, the self.control.close() is triggering the close event that somehow goes through another code path that sets self.control = None before the execution continues. That's why your fix worked, not because it was keeping the object alive longer. I think your fix was fine, it may just need a better comment.

from pyface.