Deleted issue Type of "Requirement" causing error in filters and agile board

This has similar symptoms as XRAY-292

In an agile Kanban board a custom issue of type Requirement is deleted.
The issue is still visible on the board and any filters, but an error is popped up stating "Issue does not exist".
Deleted Issue shows up in filters and selecting the issue gives an error.

A full system re-index removes the issue from agile boards and filters, but this needed every time (and regular users do not have this ability).