[Error Message Popup] Declare war on the fallen kobolds

Version 3.5.40.39999
If there is a faction of kobolds on the map that you have found, then if another player (or bot) destroys them, then on the neutral faction panel, the dead kobolds will still have the option to "Declare War". If you click on this button, an Error Message Popup will appear.
This was discovered while playing solo conquest.