fix: Check for PlatformPeg instance in session lock.

Author: kaylendog

src/components/structures/MatrixChat.tsx

@@ -313,7 +313,8 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
     private async initSession(): Promise<void> {
         // The Rust Crypto SDK will break if two Element instances try to use the same datastore at once, so
         // make sure we are the only Element instance in town (on this browser/domain).
-        if (!(await PlatformPeg.get()?.getSessionLock(() => this.onSessionLockStolen()))) {
+        const platform = PlatformPeg.get();
+        if (platform && !(await platform.getSessionLock(() => this.onSessionLockStolen()))) {
             // we failed to get the lock. onSessionLockStolen should already have been called, so nothing left to do.
             return;
         }
@@ -478,7 +479,8 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
         // mounted.
         if (!this.sessionLoadStarted) {
             this.sessionLoadStarted = true;
-            if (!PlatformPeg.get()?.checkSessionLockFree()) {
+            const platform = PlatformPeg.get();
+            if (platform && !platform.checkSessionLockFree()) {
                 // another instance holds the lock; confirm its theft before proceeding
                 setTimeout(() => this.setState({ view: Views.CONFIRM_LOCK_THEFT }), 0);
             } else {

test/test-utils/platform.ts

@@ -10,6 +10,7 @@ import { type MethodLikeKeys, mocked, type MockedObject } from "jest-mock";
 
 import BasePlatform from "../../src/BasePlatform";
 import PlatformPeg from "../../src/PlatformPeg";
+import * as SessionLock from "../../src/utils/SessionLock";
 
 // doesn't implement abstract
 // @ts-ignore
@@ -18,6 +19,14 @@ class MockPlatform extends BasePlatform {
         super();
         Object.assign(this, platformMocks);
     }
+
+    public async checkSessionLockFree(): Promise<boolean> {
+        return SessionLock.checkSessionLockFree();
+    }
+
+    public async getSessionLock(onNewInstance: () => Promise<void>): Promise<boolean> {
+        return SessionLock.getSessionLock(onNewInstance);
+    }
 }
 /**
  * Mock Platform Peg

test/unit-tests/components/structures/MatrixChat-test.tsx

@@ -1632,6 +1632,10 @@ describe("<MatrixChat />", () => {
     });
 
     describe("Multi-tab lockout", () => {
+        beforeEach(() => {
+            mockPlatformPeg();
+        });
+
         afterEach(() => {
             Lifecycle.setSessionLockNotStolen();
         });
@@ -1677,6 +1681,8 @@ describe("<MatrixChat />", () => {
             beforeEach(() => {
                 // make sure we start from a clean DOM for each of these tests
                 document.body.replaceChildren();
+                // use the MockPlatform
+                mockPlatformPeg();
             });
 
             function simulateSessionLockClaim() {