I'm making a monster collecting game, and the player itself doesn't count as an actor. In the beginning of the game, you don't have any monsters, but I still wanted the item menu accessible. This is just for show, since you won't be receiving any items until you get your first monster anyways.What kind of item do you plan to use if there are no actors?
The player can't do anything without actors, and there are no parameters to base an effect on or to be the target of an effect - so there is no need or use for regular item functions.
Just activating the menu in such a case will cause a lot of problems for the engine - so whoever will try to solve this for you needs to know what functions to allow and what functions to block.