Grabbed dndbeyond's source code

```
~/go/bin/sourcemapper -output ddb -jsurl https://media.dndbeyond.com/character-app/static/js/main.90aa78c5.js
```

ddb_main/tools/js/Shared/stores/StateStoreUtils.ts

@@ -0,0 +1,52 @@
+import { applyMiddleware, createStore, Reducer, Store } from "redux";
+import { composeWithDevTools } from "redux-devtools-extension";
+import createSagaMiddleware from "redux-saga";
+
+import {
+  defaultSaga,
+  ApiAdapterException,
+  OverrideApiException,
+} from "@dndbeyond/character-rules-engine/es";
+
+import { rollResultSaga } from "../sagas";
+import { AppLoggerUtils } from "../utils";
+
+let store: Store | null = null;
+
+export function getAppStore(): Store | null {
+  return store;
+}
+
+export function configureStore(
+  initialState: any,
+  rootReducer: Reducer,
+  sagaMiddleware: Array<any> = [],
+  middleware: Array<any> = []
+): Store {
+  const storeSagaMiddleware = createSagaMiddleware({
+    onError: (error, errorInfo) => {
+      // ApiAdapterException errors are handled by the AppApiAdapter
+      if (!(error instanceof ApiAdapterException)) {
+        AppLoggerUtils.logError(error);
+      }
+    },
+  });
+
+  let storeMiddleware: Array<any> = [];
+  storeMiddleware.push(...middleware);
+  storeMiddleware.push(storeSagaMiddleware);
+
+  store = createStore(
+    rootReducer,
+    initialState,
+    composeWithDevTools(applyMiddleware(...storeMiddleware))
+  );
+
+  storeSagaMiddleware.run(defaultSaga);
+  storeSagaMiddleware.run(rollResultSaga);
+  for (let i = 0; i < sagaMiddleware.length; i++) {
+    storeSagaMiddleware.run(sagaMiddleware[i]);
+  }
+
+  return store;
+}