Conform more of the codebase to strictNullChecks (#10738)

src/components/structures/MatrixChat.tsx

@@ -164,7 +164,7 @@ interface IProps {
     onNewScreen: (screen: string, replaceLast: boolean) => void;
     enableGuest?: boolean;
     // the queryParams extracted from the [real] query-string of the URI
-    realQueryParams?: QueryDict;
+    realQueryParams: QueryDict;
     // the initial queryParams extracted from the hash-fragment of the URI
     startingFragmentQueryParams?: QueryDict;
     // called when we have completed a token login