isValidItemId
Checks whether a authored item definition exists for the given item ID.
Return
true if the item ID is registered in FMM's item definitions
Parameters
itemId
the item ID (FMM config filename without .yml)
Checks whether a authored item definition exists for the given item ID.
true if the item ID is registered in FMM's item definitions
the item ID (FMM config filename without .yml)