Auth check fails on missing request data

[sergei-maertens]

https://github.com/VNG-Realisatie/gemma-zaakregistratiecomponent/pull/53/files

ERROR: test_create_zaakobject_limited_to_authorized_zaken (zrc.api.tests.test_auth.ZaakObjectTests) (vertrouwelijkheidaanduiding='vertrouwelijk', zaaktype='https://zaaktype.nl/ok')
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Traceback (most recent call last):
  File "/home/bbt/code/zaken/zrc/src/zrc/api/tests/test_auth.py", line 272, in test_create_zaakobject_limited_to_authorized_zaken
    response = self.client.post(url, {})
  File "/home/bbt/.virtualenvs/zrc/lib/python3.6/site-packages/rest_framework/test.py", line 300, in post
    path, data=data, format=format, content_type=content_type, **extra)
  File "/home/bbt/.virtualenvs/zrc/lib/python3.6/site-packages/rest_framework/test.py", line 213, in post
    return self.generic('POST', path, data, content_type, **extra)
  File "/home/bbt/.virtualenvs/zrc/lib/python3.6/site-packages/rest_framework/test.py", line 238, in generic
    method, path, data, content_type, secure, **extra)
  File "/home/bbt/.virtualenvs/zrc/lib/python3.6/site-packages/django/test/client.py", line 404, in generic
    return self.request(**r)
  File "/home/bbt/.virtualenvs/zrc/lib/python3.6/site-packages/rest_framework/test.py", line 289, in request
    return super(APIClient, self).request(**kwargs)
  File "/home/bbt/.virtualenvs/zrc/lib/python3.6/site-packages/rest_framework/test.py", line 241, in request
    request = super(APIRequestFactory, self).request(**kwargs)
  File "/home/bbt/.virtualenvs/zrc/lib/python3.6/site-packages/django/test/client.py", line 485, in request
    raise exc_value
  File "/home/bbt/.virtualenvs/zrc/lib/python3.6/site-packages/django/core/handlers/exception.py", line 35, in inner
    response = get_response(request)
  File "/home/bbt/.virtualenvs/zrc/lib/python3.6/site-packages/django/core/handlers/base.py", line 128, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "/home/bbt/.virtualenvs/zrc/lib/python3.6/site-packages/django/core/handlers/base.py", line 126, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/home/bbt/.virtualenvs/zrc/lib/python3.6/site-packages/django/views/decorators/csrf.py", line 54, in wrapped_view
    return view_func(*args, **kwargs)
  File "/home/bbt/.virtualenvs/zrc/lib/python3.6/site-packages/rest_framework/viewsets.py", line 103, in view
    return self.dispatch(request, *args, **kwargs)
  File "/home/bbt/.virtualenvs/zrc/lib/python3.6/site-packages/rest_framework/views.py", line 483, in dispatch
    response = self.handle_exception(exc)
  File "/home/bbt/.virtualenvs/zrc/lib/python3.6/site-packages/rest_framework/views.py", line 443, in handle_exception
    self.raise_uncaught_exception(exc)
  File "/home/bbt/.virtualenvs/zrc/lib/python3.6/site-packages/rest_framework/views.py", line 471, in dispatch
    self.initial(request, *args, **kwargs)
  File "/home/bbt/.virtualenvs/zrc/lib/python3.6/site-packages/rest_framework/views.py", line 389, in initial
    self.check_permissions(request)
  File "/home/bbt/.virtualenvs/zrc/lib/python3.6/site-packages/rest_framework/views.py", line 322, in check_permissions
    if not permission.has_permission(request, self):
  File "/home/bbt/code/zaken/vng-api-common/vng_api_common/permissions.py", line 99, in has_permission
    zaaktype = self.get_zaaktype_from_request(request)
  File "/home/bbt/code/zaken/vng-api-common/vng_api_common/permissions.py", line 152, in get_zaaktype_from_request
    zaak_url = urlparse(request.data['zaak']).path
KeyError: 'zaak'