[Sprint/PinkPanther](fix): Check whether $updateMarker exists before unsubscribing #1982
Summary
Issue in sentry at https://sentry.io/organizations/minds-inc/issues/1210702781/?project=1538008&referrer=gitlab_integration
Seems to be that if the updateMarker$ object does not exist an error is thrown.
Testing
Not sure of a method to replicate the issue.