docs: public void loadClassifier(File file) {
      try {
        if (file != null) {
          classifier = CRFClassifier.getClassifier(file);
        } else {
          // default classifier in jar
          classifier = CRFClassifier.getDefaultClassifier();
        }
      } catch (Throwable e) {
        // we catch Throwable, since we'd also like to be able to get an
        // OutOfMemoryError
        String message;
        if (file != null) {
          message = "Error loading CRF: " + file.getAbsolutePath();
        } else {
          message = "Error loading default CRF";
        }
        System.err.println(message);
        String title = "CRF Load Error";
        String msg = e.toString();
        if (msg != null) {
          message += "\n" + msg;
        }
        displayError(title, message);
        return;
      }
      removeTags();
      buildTagPanel();
      // buildExtractButton();
      extractButton.setEnabled(true);
      extract.setEnabled(true);
    }