Fix #5369 - Broken activities cause issues in migrations

Fix #5369 - Broken activities cause issues in migrations

This fixes a few bugs in previous migrations and then also introduces a new
migration for those who had run the previous migrations without encountering
the bugs to ensure that the database is in the same state as those who ran it
after the bug fixes introduced in this commit.

The commit also ensures that all activities are valid, they should be but they
might not be so checks, from now on we should be able to assume that all activities
will always be valid.