slapos_cloud: assert project reference is provided

master/bt5/slapos_cloud/WorkflowTemplateItem/portal_workflow/person_slap_interface_workflow/script_Person_requestSoftwareInstance.py

@@ -31,6 +31,7 @@ if (portal.portal_activities.countMessageWithTag(tag) > 0):
   raise NotImplementedError(tag)
 
 # Ensure project is correctly set
+assert project_reference, 'No project reference'
 project_list = portal.portal_catalog.portal_catalog(portal_type='Project', reference=project_reference,
                                                     validation_state='validated', limit=2)
 if len(project_list) != 1: