productivity/gnucash crashes when marking a bill as paid

[Rubén Llorente]

Hi there. I am experiencing a reproductible crash on 
productivity/gnucash (version 5.13 on OpenBSD 7.8 amd64).

Steps to reproduce:
Create a bill related to a provider.
Account the bill.
Try to mark the bill as paid against any of your accounts (ie. one of 
your bank accounts).

Gnucash hangs for a couple of seconds, then crashes.