Ensure AsyncStoreWithClient can start mid-lifecycle

In some cases we're likely to miss the PREPARED sync, so just handle ourselves as ready if we have a client set.

src/stores/AsyncStoreWithClient.ts

@@ -17,12 +17,25 @@ limitations under the License.
 import { MatrixClient } from "matrix-js-sdk/src/client";
 import { AsyncStore } from "./AsyncStore";
 import { ActionPayload } from "../dispatcher/payloads";
+import { Dispatcher } from "flux";
+import { MatrixClientPeg } from "../MatrixClientPeg";
 
 export abstract class AsyncStoreWithClient<T extends Object> extends AsyncStore<T> {
     protected matrixClient: MatrixClient;
 
     protected abstract async onAction(payload: ActionPayload);
 
+    protected constructor(dispatcher: Dispatcher<ActionPayload>, initialState: T = <T>{}) {
+        super(dispatcher, initialState);
+
+        if (MatrixClientPeg.get()) {
+            this.matrixClient = MatrixClientPeg.get();
+
+            // noinspection JSIgnoredPromiseFromCall
+            this.onReady();
+        }
+    }
+
     protected async onReady() {
         // Default implementation is to do nothing.
     }
@@ -40,8 +53,13 @@ export abstract class AsyncStoreWithClient<T extends Object> extends AsyncStore<
                 return;
             }
 
+            if (this.matrixClient !== payload.matrixClient) {
+                if (this.matrixClient) {
+                    await this.onNotReady();
+                }
                 this.matrixClient = payload.matrixClient;
                 await this.onReady();
+            }
         } else if (payload.action === 'on_client_not_viable' || payload.action === 'on_logged_out') {
             if (this.matrixClient) {
                 await this.onNotReady();