Apply strictNullChecks to src/components/auth/* (#10484

* Apply `strictNullChecks` to `src/components/auth/*`

* fix

* strict types

src/components/structures/auth/header/AuthHeaderContext.tsx

@@ -23,4 +23,4 @@ interface AuthHeaderContextType {
     dispatch: Dispatch<ReducerAction<AuthHeaderReducer>>;
 }
 
-export const AuthHeaderContext = createContext<AuthHeaderContextType>(undefined);
+export const AuthHeaderContext = createContext<AuthHeaderContextType | undefined>(undefined);

src/components/structures/auth/header/AuthHeaderDisplay.tsx

@@ -29,7 +29,7 @@ export function AuthHeaderDisplay({ title, icon, serverPicker, children }: Props
     if (!context) {
         return <></>;
     }
-    const current = context.state.length ? context.state[0] : null;
+    const current = context.state[0] ?? null;
     return (
         <Fragment>
             {current?.icon ?? icon}

src/components/structures/auth/header/AuthHeaderModifier.tsx

@@ -27,7 +27,7 @@ interface Props {
 
 export function AuthHeaderModifier(props: Props): null {
     const context = useContext(AuthHeaderContext);
-    const dispatch = context ? context.dispatch : null;
+    const dispatch = context?.dispatch ?? null;
     useEffect(() => {
         if (!dispatch) {
             return;