This should be safe to call if there is no running web content process. Instead, it currently crashes due to m_process->connection() being null.
Created attachment 385727 [details]
Speculative fix for <rdar://problem/57463469>, since I'm unable to reproduce it :/
Created attachment 385728 [details]
Comment on attachment 385728 [details]
Clearing flags on attachment: 385728
Committed r253543: <https://trac.webkit.org/changeset/253543>
All reviewed patches have been landed. Closing bug.