--- in place of expiry for some users

In the list of people the link is being sent to.
At one point there were some with a --- in place of the link expiry date.

This is from a report, and not sure how to reproduce this

The report concerns the list of people receiving a link and the displayed link expiry date, but it names no files, tests, or entry points. Start by locating the list rendering and expiry-value handling, then determine whether a reproducible case can be made; done means identifying and correcting the condition that displays --- instead of an expiry date.

Written by the indexing model from the issue text.