After using newest versions (for 1.12.2) of LittleTiles and CreativeCore, I still have problems when trying to create doors, game still crashes again and again.
crash-2022-01-10_09.59.06-client.txt

Something is wrong. Either the structure you are using is corrupted somehow or there is a mod interfering. Try to create a new door. Otherwise provide a screenshot and explain what exactly you are doing.