Issue Types all showing as not being associated with a Scheme after deleting an Issue Type

The user is unable to create an issue after an issue type has been deleted. The Issue Type screens shows all the issue types as not being associated with an issue type scheme, however the issue type schemes are still present.

Steps to reproduce:

• Delete an issue type
• GET A 500 ERROR (not reproducible every time)
• Click delete on the issue type that was being deleted
• Get the below error with only a cancel button

Expected behavior
When clicking on the Create button, issue type drop down should be visible.
The default issue type scheme should not have double up issue types.
The issue types should all show as being associated with an issue type scheme.
Deleting an issue type should have a delete and cancel button present.

Actual behavior
(creating an issue) There is only a project drop down
(viewing issue type scheme) The default issue type scheme is showing two of most issue types (e.g. "Issue", and then "Issue" again)
(viewing issue types) All issue types are showing as not having any associated issue type scheme
(deleting an issue type) There is only a cancel link displayed.

Workaround:

• Open the Default Issue Type Scheme
• Click the Save button
• Everything returns to normal