CODE EXAMPLE FOR JAVASCRIPT

Context: Cannot read properties of undefined

function App = () => {
   const [signedIn, setSignedIn] = useState(0)

   const contextValue = React.useMemo(() => ({signedIn, setSignedIn}), [singedIn])

    // your application structure must be wrapped inside here.
   // as an example I have only used ProfileScreen. 
   // Usually this is your root stack.
   return (
       <SignedContext.Provider value ={contextValue}>
          <ProfileScreen />
       </SignedContext.Provider>
   )
}