gistfile1.txt

// Old 
    const result = await rp(options)
    if (!result.ok) {
        console.error("The request was not ok: " + JSON.stringify(result));
        return response.header("Location", `https://us-central1-teamsync-working-v2.firebaseapp.com`).send(302);
    }

    await admin.database().ref("installations").child(result.team_id).set({
        token: result.access_token,
        team: result.team_id,
        webhook: {
            url: result.incoming_webhook.url,
            channel: result.incoming_webhook.channel_id
        }
    });

    response.header("Location", `https://us-central1-teamsync-working-v2.firebaseapp.com/success.html`).send(302);
    
// New

rp(options)
.then(function (result) {
    if (!result.ok) {
        console.error("The request was not ok: " + JSON.stringify(result));
        return response.header("Location", `https://us-central1-teamsync-working-v2.firebaseapp.com`).send(302);
    }
    
    return admin.database().ref("installations").child(result.team_id).set({
        token: result.access_token,
        team: result.team_id,
        webhook: {
            url: result.incoming_webhook.url,
            channel: result.incoming_webhook.channel_id
        }
    })
    .then(function () {
        response.header("Location", `https://us-central1-teamsync-working-v2.firebaseapp.com/success.html`).send(302);
    })
})