if the argument of #TP is null, it throws an exception that's rather very ambiguous to the users since there are two overloaded methods: Player#teleport(Location) and Player#teleport(Entity)

Javascript engine will report that this is ambiguous since it doesn't know which one to use as the parameter is null, which doesn't have a type.

#TP must check if the input is null first before executing the method. (or even better to check whether the input is Entity or Location)