Error for datasets without a link showcase

[MandanaMoshref]

on the dataset page, when I click on showcase, I receive an error if that dataset has no showcase related to.

error:
[Fri May 22 01:32:08.491996 2020] [wsgi:error] [pid 308:tid 140172595459840] [remote 129.187.100.113:57472] File '/usr/lib/ckan/default/lib/python2.7/site-packages/ckanext_showcase-1.2.1-py2.7.egg/ckanext/showcase/controller.py', line 208 in dataset_showcase_list [Fri May 22 01:32:08.491998 2020] [wsgi:error] [pid 308:tid 140172595459840] [remote 129.187.100.113:57472] context, {'package_id': c.pkg_dict['id']}) [Fri May 22 01:32:08.492000 2020] [wsgi:error] [pid 308:tid 140172595459840] [remote 129.187.100.113:57472] File '/usr/lib/ckan/default/src/ckan/ckan/logic/__init__.py', line 464 in wrapped [Fri May 22 01:32:08.492003 2020] [wsgi:error] [pid 308:tid 140172595459840] [remote 129.187.100.113:57472] result = _action(context, data_dict, **kw) [Fri May 22 01:32:08.492005 2020] [wsgi:error] [pid 308:tid 140172595459840] [remote 129.187.100.113:57472] File '/usr/lib/ckan/default/lib/python2.7/site-packages/ckanext_showcase-1.2.1-py2.7.egg/ckanext/showcase/logic/action/get.py', line 110 in package_showcase_list [Fri May 22 01:32:08.492007 2020] [wsgi:error] [pid 308:tid 140172595459840] [remote 129.187.100.113:57472] raise toolkit.ValidationError(errors) [Fri May 22 01:32:08.492010 2020] [wsgi:error] [pid 308:tid 140172595459840] [remote 129.187.100.113:57472] ValidationError: {'package_id': [u'Nicht gefunden: Datensatz']}

CKAN version 2.8.0