private int numMisses(int end) {
      int numMisses = 0;
      if (myErrors != null && end > 0) {
        for (ErrorWithIndex error : myErrors) {
          if (error.index < end && error.error instanceof MissError) {
            numMisses++;
          }
        }
      }
      return numMisses + (myBase == null ? 0 : myBase.numMisses(myDeriveIndex));
    }
private int numMisses(int end)