Concatting middleware causes reducer type error

[chris-m92]

I'm trying to add a custom middleware, in essence to save the user's session via localStorage whenever an action is dispatched to my store.

So far I have the saveSession.tsx file:

const saveSession = (store: any) => (next: any) => (action: any) => {
  console.log('Action: ', action)
  next(action)
}

export default saveSession

However, when attempting to concat this to the default middleware by

export const store = configureStore({
  reducer: {
    entities: undoable(combineReducers({
      marker: markerStoreReducer,
      scenario: scenarioStoreReducer,
    }), {
      ...options
    }),
    ...moreReducers
  },
  middleware: (getDefaultMiddleware) => getDefaultMiddleware().concat(saveSession)

I get the following TS error, specifically attached to the entities portion of my reducer

The weird thing is the site still runs in dev mode and adding a //@ts-ignore gets rid of the error, but what could be causing this issue?

If it helps, the entities are various entityAdapters

[markerikson]

What happens if you comment out the middleware line?

Conversely, what happens if you move the entire undoable(otherReducers) out to a separate variable, and then do reducer: {entities: theUndoableReducer}}?

[chris-m92]

Commenting out the middleware line removes the error. Even if I just do middleware: (getDefaultMiddleware) => getDefaultMiddleware() the error still exists.

However, pulling the entity reducer to

const entityReducer = undoable(
  combineReducers(
    {
      marker: markerStoreReducer,
      scenario: scenarioStoreReducer
    }
  ),
  {
    ...options
  }
)

and doing

export const store = configureStore({
  reducer: {
    entities: entityReducer,
    data: dataStoreReducer,
    preference: preferenceStoreReducer,
    ui: uiStoreReducer,
  },
  middleware: (getDefaultMiddleware) => getDefaultMiddleware()
})

seems to have done the trick.

Thank you so much!

[markerikson]

Yeah, we've seen cases where doing reducer: someFunctionThatCreatesAReducer() just doesn't work right with TS. It seems to struggle carrying some of the types through properly.