Fix muti game joining issue (#3675)

If this PR fixes an issue, link it below. If not, delete these two
lines.
Resolves #3669 

## Description:

Added a check to make sure that there is only one active lobbyHandle by
checking if there has been a new event before it finished processing.

## Please complete the following:

- [X] I have added screenshots for all UI updates
- [X] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [X] I have added relevant tests to the test directory
- [X] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## Please put your Discord username so you can be contacted if a bug or
regression is found:

babyboucher

src/client/Main.ts

@@ -246,6 +246,7 @@ class Client {
   private storeModal: StoreModal;
   private tokenLoginModal: TokenLoginModal;
   private matchmakingModal: MatchmakingModal;
+  private mostRecentJoinEvent: number;
 
   private turnstileTokenPromise: Promise<{
     token: string;
@@ -739,6 +740,7 @@ class Client {
 
   private async handleJoinLobby(event: CustomEvent<JoinLobbyEvent>) {
     const lobby = event.detail;
+    this.mostRecentJoinEvent = event.timeStamp;
     if (this.usernameInput && !this.usernameInput.validateOrShowError()) {
       return;
     }
@@ -757,7 +759,7 @@ class Client {
     if (lobby.source !== "public") {
       this.updateJoinUrlForShare(lobby.gameID, config);
     }
-    this.lobbyHandle = joinLobby(this.eventBus, {
+    const newLobbyHandle = joinLobby(this.eventBus, {
       gameID: lobby.gameID,
       serverConfig: config,
       cosmetics: await getPlayerCosmeticsRefs(),
@@ -768,6 +770,14 @@ class Client {
       gameRecord: lobby.gameRecord,
     });
 
+    if (this.mostRecentJoinEvent !== event.timeStamp) {
+      newLobbyHandle.stop(true);
+      console.warn("Join requested, but was superseded");
+      return;
+    }
+
+    this.lobbyHandle = newLobbyHandle;
+
     this.lobbyHandle.prestart.then(() => {
       console.log("Closing modals");
       document.getElementById("settings-button")?.classList.add("hidden");