prevent double free on olm account when logging out

by ensuring we only dispose the e2ee/Account once, as well as
the Session and other classes

src/matrix/Session.js

@@ -374,12 +374,17 @@ export class Session {
 
     dispose() {
         this._olmWorker?.dispose();
+        this._olmWorker = undefined;
         this._sessionBackup?.dispose();
+        this._sessionBackup = undefined;
         this._megolmDecryption.dispose();
+        this._megolmDecryption = undefined;
         this._e2eeAccount?.dispose();
+        this._e2eeAccount = undefined;
         for (const room of this._rooms.values()) {
             room.dispose();
         }
+        this._rooms = undefined;
     }
 
     /**

src/matrix/SessionContainer.js

@@ -384,12 +384,15 @@ export class SessionContainer {
         this._reconnector = null;
         if (this._requestScheduler) {
             this._requestScheduler.stop();
+            this._requestScheduler = null;
         }
         if (this._sync) {
             this._sync.stop();
+            this._sync = null;
         }
         if (this._session) {
             this._session.dispose();
+            this._session = null;
         }
         if (this._waitForFirstSyncHandle) {
             this._waitForFirstSyncHandle.dispose();

src/matrix/e2ee/Account.js

@@ -311,5 +311,6 @@ export class Account {
 
     dispose() {
         this._account.free();
+        this._account = undefined;
     }
 }

src/matrix/e2ee/megolm/decryption/KeyLoader.ts

@@ -212,6 +212,7 @@ class KeyOperation {
 
     dispose() {
         this.session.free();
+        this.session = undefined as any;
     }
 
     /** returns whether the key for this operation has been checked at some point against storage