Make more code conform to strict null checks (#10219

* Make more code conform to strict null checks

* Fix types

* Fix tests

* Fix remaining test assertions

* Iterate PR

test/components/views/dialogs/InteractiveAuthDialog-test.tsx

@@ -39,7 +39,7 @@ describe("InteractiveAuthDialog", function () {
 
     beforeEach(function () {
         jest.clearAllMocks();
-        mockClient.credentials = null;
+        mockClient.credentials = { userId: null };
     });
 
     afterAll(() => {

test/components/views/dialogs/SpotlightDialog-test.tsx

@@ -97,7 +97,7 @@ function mockClient({
         );
         return Promise.resolve({
             results: results.slice(0, limit ?? +Infinity),
-            limited: limit && limit < results.length,
+            limited: !!limit && limit < results.length,
         });
     });
     cli.getProfileInfo = jest.fn(async (userId) => {

test/components/views/dialogs/UserSettingsDialog-test.tsx

@@ -74,8 +74,8 @@ describe("<UserSettingsDialog />", () => {
     });
 
     const getActiveTabLabel = (container: Element) =>
-        container.querySelector(".mx_TabbedView_tabLabel_active").textContent;
-    const getActiveTabHeading = (container: Element) => container.querySelector(".mx_SettingsTab_heading").textContent;
+        container.querySelector(".mx_TabbedView_tabLabel_active")?.textContent;
+    const getActiveTabHeading = (container: Element) => container.querySelector(".mx_SettingsTab_heading")?.textContent;
 
     it("should render general settings tab when no initialTabId", () => {
         const { container } = render(getComponent());