void clearSyntaxErrorFlag(@NotNull PsiTreeChangeEvent event) {
    PsiFile file = event.getFile();
    if (file == null) return;
    VirtualFile virtualFile = file.getVirtualFile();
    if (virtualFile == null) return;
    ProblemFileInfo info = myProblems.get(virtualFile);
    if (info != null) {
      info.hasSyntaxErrors = false;
    }
  }
void clearSyntaxErrorFlag(@NotNull PsiTreeChangeEvent event)