PosthogAnalytics unwatch settings on logout (matrix-org#11207)

* PosthogAnalytics unwatch settings on logout

* Tidy

Author: t3chguy

src/Lifecycle.ts

@@ -748,11 +748,12 @@ let _isLoggingOut = false;
  * Logs the current session out and transitions to the logged-out state
  */
 export function logout(): void {
-    if (!MatrixClientPeg.get()) return;
+    const client = MatrixClientPeg.get();
+    if (!client) return;
 
     PosthogAnalytics.instance.logout();
 
-    if (MatrixClientPeg.get()!.isGuest()) {
+    if (client.isGuest()) {
         // logout doesn't work for guest sessions
         // Also we sometimes want to re-log in a guest session if we abort the login.
         // defer until next tick because it calls a synchronous dispatch, and we are likely here from a dispatch.
@@ -761,7 +762,6 @@ export function logout(): void {
     }
 
     _isLoggingOut = true;
-    const client = MatrixClientPeg.get()!;
     PlatformPeg.get()?.destroyPickleKey(client.getSafeUserId(), client.getDeviceId() ?? "");
     client.logout(true).then(onLoggedOut, (err) => {
         // Just throwing an error here is going to be very unhelpful

src/PosthogAnalytics.ts

@@ -138,6 +138,7 @@ export class PosthogAnalytics {
     private propertiesForNextEvent: Partial<Record<"$set" | "$set_once", UserProperties>> = {};
     private userPropertyCache: UserProperties = {};
     private authenticationType: Signup["authenticationType"] = "Other";
+    private watchSettingRef?: string;
 
     public static get instance(): PosthogAnalytics {
         if (!this._instance) {
@@ -337,6 +338,7 @@ export class PosthogAnalytics {
         if (this.enabled) {
             this.posthog.reset();
         }
+        if (this.watchSettingRef) SettingsStore.unwatchSetting(this.watchSettingRef);
         this.setAnonymity(Anonymity.Disabled);
     }
 
@@ -400,7 +402,7 @@ export class PosthogAnalytics {
         //  * When the user changes their preferences on this device
         // Note that for new accounts, pseudonymousAnalyticsOptIn won't be set, so updateAnonymityFromSettings
         // won't be called (i.e. this.anonymity will be left as the default, until the setting changes)
-        SettingsStore.watchSetting(
+        this.watchSettingRef = SettingsStore.watchSetting(
             "pseudonymousAnalyticsOptIn",
             null,
             (originalSettingName, changedInRoomId, atLevel, newValueAtLevel, newValue) => {