Deleting User will cause WSOD on migrated comments

I couldn't find another issue related to this, but as the title states, there is an issue. We migrated a site from D7 to D8 and a month or so later, removed some older users. Some of these users left comments on nodes and when we try to visit those nodes, we get a WSOD.

The error that generates from that is this:

Error: Call to a member function label() on null in Drupal\comment\Entity\Comment->getAuthorName() (line 408 of /app/web/core/modules/comment/src/Entity/Comment.php)

The code surrounding this is checking for target_id first then grabbing entity->label() from the object. That doesn't seem correct and I am attaching a patch to address this.