AV in Contains function

[rgreat]

Fix:

function TBaseJSON<T, Typ>.GetData(Key: Typ): IJSONAncestor;
var
  P: IJsonPair;
begin
  if Self.InheritsFrom(TSuperObject) then begin
     if Assigned(FInterface) then begin // <--------- this one
       P := TJSONObject(FInterface).Get(PString(@Key)^);
       if Assigned(P) then begin
         Result := P.JsonValue
       end else begin
         Result := Nil;
       end;
     end else begin
       Result := Nil;
     end;
  end else begin
    if Self.InheritsFrom(TSuperArray) then begin
       // Maybe we need to check for Assigned(FInterface) here too?
       Result := TJSONArray(FInterface).Get(PInteger(@Key)^);
    end;
  end;
end;