Connection::addWorkQueueMessageReceiver(..., this,...) from the constructor is incorrect, since it passed 'this' which has not-yet-constructed vptr. See the See also bugs.
Created attachment 420674 [details] Patch
Created attachment 420683 [details] Patch
Committed r273139: <https://commits.webkit.org/r273139> All reviewed patches have been landed. Closing bug and clearing flags on attachment 420683 [details].
<rdar://problem/74522756>