Nested Queries not being called in MariaDB using nodeJS - mysql

Question

This is my first project using MySQL and NodeJS, I am used to Mongo, so I might be doing something stupid here. Locally everything works fine (using MySQL) but when I deploy the following code to my hosting (that uses MariaDB) only the parent query inserts into the table (leads). The other table stays empty. Another issue is I don't have access to the NodeJS logs when it is deployed, but as far as I can tell the nested queries never get called.
var mysql = require('mysql');
global.db = mysql.createPool({
host : 'localhost',
user : 'client',
password : '******',
database : 'db'
});
router.post('/', function(req, res){
const d = req.body
let subscribe = (d.subscribe ? 1 : 0)
global.db.getConnection((err, conn) => {
if (err) {
res.end(JSON.stringify(err));
} else {
let lead = [null, d.voornaam, d.achternaam, d.email, d.postcode, d.opmerkingen, d.soort, subscribe]
let sql = 'INSERT INTO leads VALUES ?';
conn.query(sql, [[lead]], (err, results) => {
if (err) {
res.end(JSON.stringify(err));
conn.release();
} else {
const lead_id = results.insertId
d.types.forEach(w => {
let wens = [null, lead_id, w.woningType, w.slaapkamers, w.prijs, w.oplevering]
let sql = 'INSERT INTO wensen VALUES ?';
conn.query(sql, [[wens]], (err, results) => {
if(err) {
res.end(JSON.stringify(err));
conn.release();
}
})
})
res.end('True');
conn.release();
}
})
}
})
});

Answer 1

Check syntax. Note parens:
'INSERT INTO leads VALUES (?)'
Did this fail to tell you that?
if (err) { res.end(JSON.stringify(err)); ... }