QAction object does not support indexing

Reported via the support system: https://support.openlp.org/scp/tickets.php?id=4134

Traceback (most recent call last):
  File "openlp/core/ui/mainwindow.py", line 1107, in closeEvent
  File "openlp/core/ui/mainwindow.py", line 1129, in clean_up
  File "openlp/core/lib/pluginmanager.py", line 189, in finalise_plugins
  File "/Volumes/OpenLP 2.4.5/OpenLP.app/Contents/MacOS/plugins/songs/songsplugin.py", line 333, in finalise
    action_list.remove_action(self.song_import_item, UiStrings().Import)
  File "openlp/core/utils/actions.py", line 300, in remove_action
  File "openlp/core/utils/actions.py", line 117, in remove
TypeError: 'QAction' object does not support indexing

"I saved the service file (going to file - save as) and shut the programme down, but when I went to open it again it would not open and kept coming up with the bug error. I had to restart my computer to reopen the file and I've since been able to open it again with no problems."

This was on macOS.