I'm trying to create protected router through route handlers but I'm getting the error "TypeError: module1.render is not a function".
This is my code:

export async function GET(request: NextRequest) {
    const auth = getAuth(firebase_app);
    onAuthStateChanged(auth, (user) => {
        if (user) {
            return NextResponse.next()
        } else {
            return NextResponse.redirect("/")
        }
    })
}

What am I doing wrong?