Errors/Crashes on deleting attack methods

[Gambit37]

Trying to delete a bitmap used by a flying spell in the Add/Remove graphics section.

"This object is used by ATTACK_METHOD_X. Delete that method before deleting this object"

Trying to delete the attack method crashes the editor:

Error:
an access violation exception.

Stack Dump:
RTCEditDlgNewMethods.OnButtonDelete();
RTCEditView.OnResourceMethods();
RTCEditApp.WinMain();