Fix Grenade Launcher with Null Errors

Changes (Non-Breaking):

Custom Items:

Grenade Launcher (ADATS):

Now properly reloads SCP-018.
Now launches SCP-018, Coal, Coal?, and Snowballs without throwing a null error.
Note: SCP-018, Coal, Coal?, and Snowballs will NOT respect the "Impact or Roller" settings as SCP-018 will not detonate on initial surface hit, and Coal, Coal?, and Snowballs will always break on surface hit. There's nothing much I can do about this, sorry.