I am always getting a pending promise even though I have followed everything mention in jwt documentation https://wordpress.org/plugins/jwt-auth/#description I have defined the auth secret key and even changed the .htaccess file but the promise is still pending here below is my code

fetch('https://mangareadhere.xyz/wp-json/jwt-auth/v1/token',{
    method: "POST",
    headers:{
        'Content-Type': 'application/json',
        'accept': 'application/json',
    },

    body:JSON.stringify({    
        "username": username, 
    "password": password

    })
    }).then(function(response){
        return response.json()
    }).then(function(user){
        console.log(user.token)
        localStorage.setItem('jwt', user.token)
    });
}

I am trying to get user token as mentioned in documentation but the promise is stucked any help would be greatly helpful.