function dispatch(action) {
  if (!isPlainObject(action)) {
    throw new Error(
      'Actions must be plain objects. ' +
        'Use custom middleware for async actions.'
    )
  }

  if (typeof action.type === 'undefined') {
    throw new Error(
      'Actions may not have an undefined "type" property. ' +
        'Have you misspelled a constant?'
    )
  }

  if (isDispatching) {
    throw new Error('Reducers may not dispatch actions.')
  }