After disabling a few items in the config the game crashed on startup with an error saying Item must be registered before assigning color handler. It seems that in ModItemColors you don't make sure that the item isn't disabled before registering a color handler for it which causes this crash.

Yeah I guess there will be issues like this. I usually don't test disabling items too much as I actually want people to use all the items. Will look into this and fix probably in the next 1.9 release.