Clean up the use of progress_stage

opentech/apply/determinations/views.py

@@ -83,12 +83,11 @@ class DeterminationCreateOrUpdateView(CreateOrUpdateView):
         return self.progress_stage(self.submission) or response
 
     def progress_stage(self, instance):
-        # TODO update post-revisions work
-        proposal_transition = instance.get_transition('draft_proposal')
-        if proposal_transition:
-            if can_proceed(proposal_transition):
-                proposal_transition(by=self.request.user)
-                instance.save()
+        try:
+            instance.perform_transition('draft_proposal', self.request.user)
+        except PermissionDenied:
+            pass
+        else:
             return HttpResponseRedirect(instance.get_absolute_url())
 
     def get_action_name_from_determination(self, determination):

opentech/apply/funds/models.py

@@ -585,6 +585,8 @@ class AddTransitions(models.base.ModelBase):
 
         def perform_transition(self, action, user):
             transition = self.get_transition(action)
+            if not transition:
+                raise PermissionDenied(f'Invalid "{ action }" transition')
             if not can_proceed(transition):
                 action = self.phase.transitions[action]
                 raise PermissionDenied(f'You do not have permission to "{ action }"')