private void registerError(@NotNull PsiElement anchor, @NotNull TypeMismatch mismatch) {
      Convertible convertible = mismatch.isConvertible();
      if (convertible == Convertible.CONVERTIBLE_MUTUAL_SUBCLASS_UNKNOWN) {
        registerPossibleProblem(anchor);
      } else {
        registerError(anchor, mismatch.getLeft(), mismatch.getRight(), convertible != Convertible.NOT_CONVERTIBLE);
      }
    }
private void registerError(@NotNull PsiElement anchor, @NotNull TypeMismatch mismatch)