workflows: don't crash on missing/previous destination status (#48992)

tests/admin_pages/test_workflow.py

@@ -1008,6 +1008,18 @@ def test_workflows_edit_choice_action_line_details(pub):
     assert resp.html.find('a', {'href': 'items/1/'}).text == \
         'Manual Jump ("Resubmit", to Resubmit, by User (and set marker))'
 
+    jump.status = 'error'
+    wf.store()
+    resp = app.get('/backoffice/workflows/%s/status/%s/' % (wf.id, st1.id))
+    assert resp.html.find('a', {'href': 'items/1/'}).text == \
+        'Manual Jump (broken, missing destination status)'
+
+    jump.status = '_previous'
+    wf.store()
+    resp = app.get('/backoffice/workflows/%s/status/%s/' % (wf.id, st1.id))
+    assert resp.html.find('a', {'href': 'items/1/'}).text == \
+        'Manual Jump ("Resubmit", to previously marked status, by User (and set marker))'
+
 
 def test_workflows_action_subpath(pub):
     create_superuser(pub)

wcs/workflows.py

@@ -2441,8 +2441,16 @@ class ChoiceWorkflowStatusItem(WorkflowStatusJumpItem):
         return _('computed label')
 
     def get_line_details(self):
-        if self.label and self.status:
-            to_status = self.parent.parent.get_status(self.status)
+        to_status = None
+        if self.status == '_previous':
+            to_status = WorkflowStatus(_('previously marked status'))
+        elif self.status:
+            try:
+                to_status = self.parent.parent.get_status(self.status)
+            except KeyError:
+                return _('broken, missing destination status')
+
+        if self.label and to_status:
             more = ''
             if self.set_marker_on_status:
                 more += ' ' + _('(and set marker)')