inject sagas into the store

registerSaga.js

// Initialize the saga middleware
const sagaMiddleware = createSagaMiddleware();

// Inject middleware to the store
const store = createStore(userReducer, applyMiddleware(sagaMiddleware));

// Run the sagas you defined. 
// You would normally have a rootSaga were you register all your saga 
// Or spread then in the run function. 
sagaMiddleware.run(watchRequest);