In either the scenario editor or in a normal game when the player has entered the /editor command (when the player is in the editor mode), the mod causes a non-recoverable error when placing ground.
https://imgur.com/t7QS9KL
The issue is probably to do with the mod wanting an item in the players hand when new ground is placed, but in the editor mode, there is no item so it indexes a null value.
Hope you can get this issue solved.
~ Ralp

Sorry I didn't address this earlier, I must have put it on my mental to-do list then forgotten it

Hey!
I'm the current maintainer of CreativeMod and I received this bug report: https://mods.factorio.com/mod/creative-mod/discussion/5d7eb68f697a83000bfa7464

The item just raises a normal "defines.events.on_player_built_tile" event and that one is apparently handled wrong in your mod.