Implementation of a parametric interface blows up the language server

[VerySpicyGames]

@sharpneck

FooModule<public> := module:
    # Case 1 inteface
    test_interface<public>(t:type) := interface:
        Foo<public>(Bar:t):void

    test_interface_implementation<public> := class(test_interface(float)):
        Foo<override>(Bar: float):void={} # Case 1 implementation: works fine

    # Case 2 interface
    test_interface_func<public>(t:type) := interface:
        Foo<public>(Callback:t->void):void

    test_interface_func_implementation := class(test_interface_func(float)):
        Foo<override>(Callback: float->void):void={} # Case 2 implementation: language server crashes, if attempting to build verse UEFN crashes too

This was changed now to a compile error saying its not implemented. This is better than crashing the lsp