public @NotNull @NonNls String diagnoseNull() {
      PsiFile file = ReadAction.compute(this::getFile);
      try {
        PsiElement element = ReadAction.compute(() -> restoreFromStubIndex((PsiFileWithStubSupport)file, myIndex, myElementType, true));
        return "No diagnostics, element=" + element + "@" + (element == null ? 0 : System.identityHashCode(element));
      }
      catch (AssertionError e) {
        String msg = e.getMessage();
        msg += file == null ? "\n no PSI file" : "\n current file stamp=" + (short)file.getModificationStamp();
        Document document = FileDocumentManager.getInstance().getCachedDocument(myVirtualFile);
        if (document != null) {
          msg += "\n committed=" + PsiDocumentManager.getInstance(myProject).isCommitted(document);
          msg += "\n saved=" + !FileDocumentManager.getInstance().isDocumentUnsaved(document);
        }
        return msg;
      }
    }
public @NotNull @NonNls String diagnoseNull()