%Error: t/t_interface_asvar_bad.v:29:16: Operator ASSIGN expected non-interface on Assign RHS but 'itf' is an interface.
                                       : ... In instance t.source
      getter = itf;   
               ^~~
%Error: t/t_interface_asvar_bad.v:30:23: Operator ADD expected non-interface on RHS but 'itf' is an interface.
                                       : ... In instance t.source
      getter = 4'd3 + itf;   
                      ^~~
%Error: Exiting due to