Instantiation fails for paramter connection in root

[lwrage]

When a feature of the instance root component is connected with a parameter connection to a subcompnent, the instantiation fails with an NPE.

To reproduce, instantiate receiver.impl in the model below.

package Issue2918
public

  thread receiver
    features
      p: in event data port Integer;
  end receiver;

  thread implementation receiver.impl
    calls
      call : { c : subprogram receiver_spg;};
    connections
      cnx: parameter p -> c.input;
  end receiver.impl;

  subprogram receiver_spg
    features
      input : in parameter Integer;
  end receiver_spg;

  data Integer
  end Integer;

end Issue2918;