Thanks to the easy handy testcase, was able to replicate the test scenario
on my local environment. And yes tbinfo->dobj.ext_member check into
getTableAttrs() do fix the issue.
Looking more into pg_dump code what I found that, generally PG don't have
tbinfo->dobj.ext_member check to ignore the object. Mostly we do this kind
of check using tbinfo->dobj.dump (look at dumpTable() for reference). Do you
have any particular reason if choosing dobj.ext_member over dobj.dump ?