Why typescript is unable to identify value provided by the context wrapper?

I am trying to create a context wrapper. Pass the state variables as provider values and try to access those values using useContext in the ToolBar component.

type NavContextType = {
    isDrawerOpen: boolean;
    setIsDrawerOpen: React.Dispatch<React.SetStateAction<boolean>>;
};

export const NavContext = createContext<NavContextType | null>(null);

const NavBar: :ReactFC<ReactNode | undefined> = ({ children }) => {
    const [isDrawerOpen, setIsDrawerOpen] = useState(false);

    return (
        <NavContext.Provider value={{ isDrawerOpen, setIsDrawerOpen }}>
            <ToolBar />
        </NavContext.Provider>
    );
};

Toolbar.js:

import { NavContext } from "./NavBar";

const ToolBar = () => {
    const { isDrawerOpen, setIsDrawerOpen } = useContext(NavContext);
    return (
        .......
        .......
    );
};

when I try to access context values using const { isDrawerOpen, setIsDrawerOpen } = useContext(NavContext);. I get typescript error as:

TS2339: Property 'setIsDrawerOpen' does not exist on type 'NavContextType | null'.
        Property 'isDrawerOpen' does not exist on type 'NavContextType | null'.

Please guide me.

>Solution :

You need to use as directive for example useContext(NavContext) as NavContextType. Typescript will know, that the value is not null.