Make more of the codebase conform to strict types (#10859)

src/stores/AutoRageshakeStore.ts

@@ -142,7 +142,11 @@ export default class AutoRageshakeStore extends AsyncStoreWithClient<IState> {
         }
     }
 
-    private async onSyncStateChange(_state: SyncState, _prevState: SyncState, data?: ISyncStateData): Promise<void> {
+    private async onSyncStateChange(
+        _state: SyncState,
+        _prevState: SyncState | null,
+        data?: ISyncStateData,
+    ): Promise<void> {
         if (!this.state.initialSyncCompleted) {
             await this.updateState({ initialSyncCompleted: !!data?.nextSyncToken });
         }