Test the RoomHeader changes

Author: robintown

package.json

@@ -138,6 +138,7 @@
     "@percy/cypress": "^3.1.1",
     "@sentry/types": "^6.10.0",
     "@sinonjs/fake-timers": "^9.1.2",
+    "@testing-library/jest-dom": "^5.16.5",
     "@testing-library/react": "^12.1.5",
     "@types/classnames": "^2.2.11",
     "@types/commonmark": "^0.27.4",

src/stores/WidgetEchoStore.ts

@@ -111,7 +111,7 @@ class WidgetEchoStore extends EventEmitter {
     }
 }
 
-let singletonWidgetEchoStore = null;
+let singletonWidgetEchoStore: WidgetEchoStore | null = null;
 if (!singletonWidgetEchoStore) {
     singletonWidgetEchoStore = new WidgetEchoStore();
 }