You must provide a root Epic to createEpicMiddleware

[temurih]

Bug Report

Current Behavior
I am encountering this ts error when I am trying to use createEpicMiddleware.
Error: Property 'run' does not exist on type 'EpicMiddleware<Action<any>, {}, any, Action<any>>'
OR
Error: You must provide a root Epic to createEpicMiddleware

Reproduction

const epicMiddleware = createEpicMiddleware({
    dependencies: { ... }
});

let middleware: Middleware[] = [];
middleware.push(epicMiddleware);
...

export const configureStore = (initialState: object): Store<IStore> => {
    const store = createStore(
        rootReducer,
        initialState,
        applyMiddleware(...middleware)
    );

    epicMiddleware.run(rootEpic);

    return store;
};

This is the error I am getting,

Property 'run' does not exist on type 'EpicMiddleware<Action<any>, {}, any, Action<any>>'.

When I change the type of epicMiddleware to any, then it throws a runtime error, You must provide a root Epic to createEpicMiddleware

P.S. I am using the latest version of redux-observable (1.0.0)

---

When using older version of redux-observable (such as 0.18.0), this works fine,

const epicMiddleware = createEpicMiddleware(rootEpic, {
    dependencies: { ... }
});

let middleware: Middleware[] = [];
middleware.push(epicMiddleware);
...

export const configureStore = (initialState: object): Store<IStore> =>
    createStore(
        rootReducer,
        initialState,
        applyMiddleware(...middleware)
    );

[evertbouw]

EpicMiddleware definitely does have the run method, so I'm going to guess this is a version mismatch in the typescript cache. The problem should disappear if you restart the typescript service/your editor after updating packages. If that doesn't work delete your node modules/lock file/clear npm cache and reinstall everything. That's probably overdoing it but it's what I do 😄

[temurih]

Well, I don't know if I want to do all that. Sounds like too much work, and still not sure if it works after. I would rather use the older version that works.

[jayphelps]

@temurih can you submit a stackblitz or repo that reproduces the issue? Here's a working example: https://stackblitz.com/edit/typescript-u6vdf4

[evertbouw]

A lot of work? Hmm it's just 3 commands and reopening your editor. It's the cure all whenever I don't trust the results

rm -rf node_modules yarn.lock
yarn cache clean
yarn