code: function _patchCodeMirror() {
          var _original_CodeMirror_defineMode = CodeMirror.defineMode;
          function _wrapped_CodeMirror_defineMode(name) {
              if (CodeMirror.modes[name]) {
                  console.error("There already is a CodeMirror mode with the name \"" + name + "\"");
                  return;
              }
              _original_CodeMirror_defineMode.apply(CodeMirror, arguments);
          }
          CodeMirror.defineMode = _wrapped_CodeMirror_defineMode;
      }
docs: Monkey-patch CodeMirror to prevent modes from being overwritten by extensions.
  We may rely on the tokens provided by some of these modes.