Perform dead code analysis with Knip (#2575)

* Install Knip

* Clarify an import that was confusing Knip

* Fix issues detected by Knip

Including cleaning up some unused code and dependencies, using a React hook that we unintentionally stopped using, and also adding some previously undeclared dependencies.

* Run dead code analysis in lint script and CI

---------

Co-authored-by: Timo <toger5@hotmail.de>

src/room/RoomPage.tsx

@@ -35,10 +35,7 @@ import { LobbyView } from "./LobbyView";
 import { E2eeType } from "../e2ee/e2eeType";
 import { useProfile } from "../profile/useProfile";
 import { useMuteStates } from "./MuteStates";
-import {
-  useSetting,
-  optInAnalytics as optInAnalyticsSetting,
-} from "../settings/settings";
+import { useOptInAnalytics } from "../settings/settings";
 
 export const RoomPage: FC = () => {
   const {
@@ -83,7 +80,7 @@ export const RoomPage: FC = () => {
     registerPasswordlessUser,
   ]);
 
-  const [optInAnalytics, setOptInAnalytics] = useSetting(optInAnalyticsSetting);
+  const [optInAnalytics, setOptInAnalytics] = useOptInAnalytics();
   useEffect(() => {
     // During the beta, opt into analytics by default
     if (optInAnalytics === null && setOptInAnalytics) setOptInAnalytics(true);

src/room/usePageUnload.ts

@@ -1,64 +0,0 @@
-/*
-Copyright 2022 New Vector Ltd
-
-Licensed under the Apache License, Version 2.0 (the "License");
-you may not use this file except in compliance with the License.
-You may obtain a copy of the License at
-
-    http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing, software
-distributed under the License is distributed on an "AS IS" BASIS,
-WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-See the License for the specific language governing permissions and
-limitations under the License.
-*/
-
-import { useEffect } from "react";
-
-import { platform } from "../Platform";
-
-export function usePageUnload(callback: () => void): void {
-  useEffect(() => {
-    let pageVisibilityTimeout: ReturnType<typeof setTimeout>;
-
-    function onBeforeUnload(event: PageTransitionEvent): void {
-      if (event.type === "visibilitychange") {
-        if (document.visibilityState === "visible") {
-          clearTimeout(pageVisibilityTimeout);
-        } else {
-          // Wait 5 seconds before closing the page to avoid accidentally leaving
-          // TODO: Make this configurable?
-          pageVisibilityTimeout = setTimeout(() => {
-            callback();
-          }, 5000);
-        }
-      } else {
-        callback();
-      }
-    }
-
-    // iOS doesn't fire beforeunload event, so leave the call when you hide the page.
-    if (platform === "ios") {
-      window.addEventListener("pagehide", onBeforeUnload);
-      // eslint-disable-next-line @typescript-eslint/ban-ts-comment
-      // @ts-ignore
-      document.addEventListener("visibilitychange", onBeforeUnload);
-    }
-
-    // eslint-disable-next-line @typescript-eslint/ban-ts-comment
-    // @ts-ignore
-    window.addEventListener("beforeunload", onBeforeUnload);
-
-    return (): void => {
-      window.removeEventListener("pagehide", onBeforeUnload);
-      // eslint-disable-next-line @typescript-eslint/ban-ts-comment
-      // @ts-ignore
-      document.removeEventListener("visibilitychange", onBeforeUnload);
-      // eslint-disable-next-line @typescript-eslint/ban-ts-comment
-      // @ts-ignore
-      window.removeEventListener("beforeunload", onBeforeUnload);
-      clearTimeout(pageVisibilityTimeout);
-    };
-  }, [callback]);
-}