Typescript error: Type 'unknown' is not assignable to type 'never'

What is the current behavior?

Redux set never as type instead of unknown:

The types of ‘router.location.state’ are incompatible between these types. Type ‘unknown’ is not assignable to type ‘never’.

Steps to Reproduce

import { connectRouter, LocationChangeAction, RouterState } from 'connected-react-router';
import { History } from 'history';
import { applyMiddleware, combineReducers, compose, createStore, Store, CombinedState, AnyAction } from 'redux';

export type ApplicationState = { router: RouterState };

const createRootReducer = (history: History) => combineReducers({
    router: connectRouter(history),
});

export default function configureStore(history: History, initialState?: ApplicationState): Store<CombinedState<any>, AnyAction | LocationChangeAction<any>> {
    const store = createStore(
        createRootReducer(history), // root reducer with router state
        initialState,
    );

    return store;
}

What is the expected behavior?

Use unknown instead of never

Environment Details

Redux 4.1.0 Chrome Windows 10 Did this work in previous versions of Redux? Yes

[phryneas]

Please see if https://github.com/reduxjs/redux/pull/4078 resolves your issue

[jucrouzet]

I encountered the same issue and #4078 fixes it.

Thanks @phryneas waiting for the PR to be merged.