ContentNode.DoesNotExist: ContentNode matching query does not exist.
No need to throw when the delete node task does not find the node it is deleting - its work is done!
Sentry Issue: [STUDIO-EF4](https://sentry.io/organizations/learningequality/issues/2448220046/?referrer=github_integration)

```
ContentNode.DoesNotExist: ContentNode matching query does not exist.
(5 additional frame(s) were not displayed)
...
  File "model_utils/tracker.py", line 65, in __set__
    getattr(instance, self.field_name)
  File "model_utils/tracker.py", line 42, in __get__
    value = self.descriptor.__get__(instance, owner)
  File "django/db/models/query_utils.py", line 144, in __get__
    instance.refresh_from_db(fields=[field_name])
  File "django/db/models/base.py", line 637, in refresh_from_db
    db_instance = db_instance_qs.get()
  File "django/db/models/query.py", line 437, in get
    self.model._meta.object_name
```
diff --git a/contentcuration/contentcuration/tasks.py b/contentcuration/contentcuration/tasks.py
index 602aebadf..e603aaedf 100644
--- a/contentcuration/contentcuration/tasks.py
+++ b/contentcuration/contentcuration/tasks.py
@@ -68,6 +68,8 @@ def delete_node_task(
                     pass
                 else:
                     raise
+            except ContentNode.DoesNotExist:
+                deleted = True
     except Exception as e:
         self.report_exception(e)
 
['contentcuration/contentcuration/tasks.py']