void removeFileLeverComponent(@NotNull FileEditor fileEditor) {
    if (fileLevelComponentsStorage instanceof Pair) {
      //noinspection unchecked
      Pair<FileEditor, JComponent> pair = (Pair<FileEditor, JComponent>)fileLevelComponentsStorage;
      if (pair.first == fileEditor) {
        fileLevelComponentsStorage = null;
      }
    }
    else if (fileLevelComponentsStorage instanceof Map) {
      //noinspection unchecked
      ((Map<FileEditor, JComponent>)fileLevelComponentsStorage).remove(fileEditor);
    }
  }
void removeFileLeverComponent(@NotNull FileEditor fileEditor)