Make a new NPC or copy of existing, give this npc the new custom spellcaster class and attempt to assign him spells.
Error will popup.
Here is prepared module with hak where Beast class is modified to be a copy of Cleric class in everything but name: repro-35.zip
Specifics
Game build: 36-9
Regression?: No, never worked.
If needed, describe the bug
The game itself handles NPCs with custom spellcaster classes, albeit I am getting some issues with them not casting some stuff but that might be related to scripting, still invedstigating. But the only way to assign such creature spells is either GFF editor or give this NPC vanilla class and then change the class ID via GFF editor in blueprint.
To Reproduce
Here is prepared module with hak where Beast class is modified to be a copy of Cleric class in everything but name: repro-35.zip
Specifics
If needed, describe the bug
The game itself handles NPCs with custom spellcaster classes, albeit I am getting some issues with them not casting some stuff but that might be related to scripting, still invedstigating. But the only way to assign such creature spells is either GFF editor or give this NPC vanilla class and then change the class ID via GFF editor in blueprint.