chore: improve general unit tests

Closes https://git.opentalk.dev/opentalk/frontend/web/web-app/-/issues/2466 https://git.opentalk.dev/opentalk/frontend/web/web-app/-/issues/2467 https://git.opentalk.dev/opentalk/frontend/web/web-app/-/issues/2468 https://git.opentalk.dev/opentalk/frontend/web/web-app/-/issues/2478 https://git.opentalk.dev/opentalk/frontend/web/web-app/-/issues/2486 https://git.opentalk.dev/opentalk/frontend/web/web-app/-/issues/2487 https://git.opentalk.dev/opentalk/frontend/web/web-app/-/issues/2494 https://git.opentalk.dev/opentalk/frontend/web/web-app/-/issues/2501 https://git.opentalk.dev/opentalk/frontend/web/web-app/-/issues/2505 https://git.opentalk.dev/opentalk/frontend/web/web-app/-/issues/2511