[Aetae]

Так?

try {
  await sqlConnection()
}
catch (e) {
  console.log(e);
}

function sqlConnection() {
  var attempts = 5;
  return new Promise(function (resolve, reject) {
    con.connect(function connect(err) {
      if (err) {
        if(attempts--) con.connect(connect);
        else reject(err);
      } else {
        console.log("Connected to mysql");
        resolve();
      }
    })
  })
}