Conform more of the code base to strict null checking (#10147)

* Conform more of the code base to strict null checking

* More strict fixes

* More strict work

* Fix missing optional type

* Iterate

test/utils/localRoom/isLocalRoom-test.ts

@@ -26,12 +26,8 @@ describe("isLocalRoom", () => {
 
     beforeEach(() => {
         const client = createTestClient();
-        room = new Room("!room:example.com", client, client.getUserId());
-        localRoom = new LocalRoom(LOCAL_ROOM_ID_PREFIX + "test", client, client.getUserId());
-    });
-
-    it("should return false for null", () => {
-        expect(isLocalRoom(null)).toBe(false);
+        room = new Room("!room:example.com", client, client.getUserId()!);
+        localRoom = new LocalRoom(LOCAL_ROOM_ID_PREFIX + "test", client, client.getUserId()!);
     });
 
     it("should return false for a Room", () => {

test/utils/localRoom/isRoomReady-test.ts

@@ -59,6 +59,7 @@ describe("isRoomReady", () => {
             beforeEach(() => {
                 mocked(client.getRoom).mockImplementation((roomId: string) => {
                     if (roomId === room1.roomId) return room1;
+                    return null;
                 });
             });