Clicking "Export to CSV" gives me Server Error (500)

[arthuredelstein]

No description provided.

[tiftran]

Sentry Logs:

TypeError: unsupported operand type(s) for -: 'NoneType' and 'datetime.date'
  File "django/core/handlers/exception.py", line 34, in inner
    response = get_response(request)
  File "django/core/handlers/base.py", line 115, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "django/core/handlers/base.py", line 113, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "django/views/decorators/csrf.py", line 54, in wrapped_view
    return view_func(*args, **kwargs)
  File "django/views/generic/base.py", line 71, in view
    return self.dispatch(request, *args, **kwargs)
  File "rest_framework/views.py", line 505, in dispatch
    response = self.handle_exception(exc)
  File "rest_framework/views.py", line 465, in handle_exception
    self.raise_uncaught_exception(exc)
  File "rest_framework/views.py", line 476, in raise_uncaught_exception
    raise exc
  File "rest_framework/views.py", line 502, in dispatch
    response = handler(request, *args, **kwargs)
  File "rest_framework/generics.py", line 199, in get
    return self.list(request, *args, **kwargs)
  File "rest_framework/mixins.py", line 46, in list
    return Response(serializer.data)
  File "rest_framework/serializers.py", line 760, in data
    ret = super().data
  File "rest_framework/serializers.py", line 260, in data
    self._data = self.to_representation(self.instance)
  File "rest_framework/serializers.py", line 677, in to_representation
    return [
  File "rest_framework/serializers.py", line 678, in <listcomp>
    self.child.to_representation(item) for item in iterable
  File "rest_framework/serializers.py", line 516, in to_representation
    attribute = field.get_attribute(instance)
  File "rest_framework/fields.py", line 454, in get_attribute
    return get_attribute(instance, self.source_attrs)
  File "rest_framework/fields.py", line 94, in get_attribute
    instance = getattr(instance, attr)
  File "experimenter/experiments/models.py", line 481, in total_duration
    return (self.end_date - self.start_date).days

Will need to poke at it some more, but initial theory is that rapid experiments and/or so other type of experiment has no proposed duration so there wasn't an end_date computed