Failed to load plugin "mousetrap_response"

I am a new user. After installing mousetrap to OpenSesame, I couldn't load examples.

Also, I found a similar error when I tried to add "mousetrap_response" to the other (non-mousetrap) sample experiments.

How can I solve this issue?

Information:

• Operating System: darwin
• OpenSesame: 3.3.0
• Python: 3.7.6

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Error message:

Traceback (most recent call last):
  File "/Applications/OpenSesame.app/Contents/Resources/lib/python3.7/site-packages/libopensesame/item_store.py", line 190, in new
    self.experiment.item_prefix()
  File "/Applications/OpenSesame.app/Contents/Resources/lib/python3.7/site-packages/libopensesame/plugins.py", line 449, in load_plugin
    item = item_class(item_name, experiment, string)
  File "/Applications/OpenSesame.app/Contents/Resources/share/opensesame_plugins/mousetrap_form/mousetrap_form.py", line 393, in __init__
    self.custom_interactions()
  File "/Applications/OpenSesame.app/Contents/Resources/share/opensesame_plugins/mousetrap_form/mousetrap_form.py", line 422, in custom_interactions
    self.cols_widget.setEnabled(present_form)
  File "/Applications/OpenSesame.app/Contents/Resources/lib/python3.7/site-packages/libopensesame/item.py", line 241, in __getattr__
    raise AttributeError(u'%s not found' % var)
AttributeError: cols_widget not found

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Applications/OpenSesame.app/Contents/Resources/lib/python3.7/site-packages/libqtopensesame/widgets/tree_overview.py", line 788, in dropEvent
    self.drop_event_item_new(data, e)
  File "/Applications/OpenSesame.app/Contents/Resources/lib/python3.7/site-packages/libqtopensesame/widgets/tree_overview.py", line 702, in drop_event_item_new
    item, new_items = self.drop_get_item_snippet(data)
  File "/Applications/OpenSesame.app/Contents/Resources/lib/python3.7/site-packages/libqtopensesame/widgets/tree_overview.py", line 588, in drop_get_item_snippet
    catch_exceptions=False)
  File "/Applications/OpenSesame.app/Contents/Resources/lib/python3.7/site-packages/libqtopensesame/misc/qtitem_store.py", line 118, in new
    allow_rename=allow_rename
  File "/Applications/OpenSesame.app/Contents/Resources/lib/python3.7/site-packages/libopensesame/item_store.py", line 195, in new
    exception=e
libopensesame.exceptions.osexception: 
Failed to load plugin 'mousetrap_form'

item-stack: 
time: Fri May  1 21:36:39 2020
exception type: AttributeError
exception message: cols_widget not found

Traceback:
  File "/Applications/OpenSesame.app/Contents/Resources/lib/python3.7/site-packages/libopensesame/item_store.py", line 190, in new
    self.experiment.item_prefix()
  File "/Applications/OpenSesame.app/Contents/Resources/lib/python3.7/site-packages/libopensesame/plugins.py", line 449, in load_plugin
    item = item_class(item_name, experiment, string)
  File "/Applications/OpenSesame.app/Contents/Resources/share/opensesame_plugins/mousetrap_form/mousetrap_form.py", line 393, in __init__
    self.custom_interactions()
  File "/Applications/OpenSesame.app/Contents/Resources/share/opensesame_plugins/mousetrap_form/mousetrap_form.py", line 422, in custom_interactions
    self.cols_widget.setEnabled(present_form)
  File "/Applications/OpenSesame.app/Contents/Resources/lib/python3.7/site-packages/libopensesame/item.py", line 241, in __getattr__
    raise AttributeError(u'%s not found' % var)
AttributeError: cols_widget not found