function createMochaInstanceAlreadyRunningError(message, instance) {
    var err = new Error(message);
    err.code = constants$4.INSTANCE_ALREADY_RUNNING;
    err.instance = instance;
    return err;
  }
Creates an error object to be thrown when a mocha object's `run` method is called while a test run is in progress.
@param {string} message The error message to be displayed.
@static
@public