redux-observable/redux-observable

Hey all,

I'm working on an epic that will asynchronously load another epic. While the epic is loading, all actions will be buffered and eventually passed through this epic.

The current implementation I'm working with:

const lazyEpic =
    (getEpicPromise: () => Promise<Epic>) =>
    (
        action$: ActionsObservableType,
        store: MiddlewareAPI,
        dependencies: BoardEpicDependencies,
    ): ObservableType<Action> => {
        const epic$ = Observable.fromPromise(getEpicPromise());

        // Buffer all actions before epic is loaded
        const actionsBeforeEpic$ = action$.buffer(epic$);

        // Run the buffered actions through the deferred epic
        const bufferedResults$ = actionsBeforeEpic$.mergeMap((actions) =>
            epic$.mergeMap((epic) => epic(ActionsObservable.of(...actions), store, dependencies)),
        );

        // Pass the active action$ stream to the deferred epic
        const normalResults$ = epic$.mergeMap((epic) => epic(action$, store, dependencies));

        return Observable.merge(normalResults$, bufferedResults$);
    };

The problem I'm having is this line, which causes a stack overflow/range error, and I can't quite figure out why:

const bufferedResults$ = actionsBeforeEpic$.mergeMap((actions) =>
            epic$.mergeMap((epic) => epic(ActionsObservable.of(...actions), store, dependencies)),  // Returning epic(ActionsObservable.of(...actions), store, dependencies)) is the culprit
        );

Wondering if there's any suggestions or obvious flaws in this implementation?