(#17) Fixed call of focus on browserWindow

Author: s1hofmann

test/window-integration-tests/test.js

@@ -14,7 +14,7 @@ beforeAll(async () => {
         waitTimeout: APP_TIMEOUT,
     });
     await app.start();
-    await app.focus();
+    await app.browserWindow.focus();
 });
 
 beforeEach(async () => {