ExportUFO-plus doesn't work

Also the UI doesn’t show anything

Details:
Traceback (most recent call last):

  File "plugin.py", line 59, in setFont_
    self.exporterView.setFont(GSFontObj)

  File "UI.py", line 459, in setFont
    self.masterExportTab.view.setFont(font)

  File "UI.py", line 98, in setFont
    self.exportUfoList.set([m.name for m in self.font.masters])
                                            ^^^^^^^^^^^^^^^^^

AttributeError: 'NoneType' object has no attribute 'masters'

App:3.2-3257 Plugin:1.0.1-4 System:13.6.6

That plugin has been abandoned, I am afraid. Try the built-in UFO export instead.