Node promises and catch issue - sql-server

Question

I am currently writing a database class that receives a node http request and saves data into a db.
It uses MSSQL (yeah...), therefore I'm using node-mssql.
I created a class to manage DB access, code:
"use strict";
var config = require('../../config/mainConfigs');
const mssql = require('mssql');
class db {
constructor(){
this._pool = null;
}
get_pool(){
if (!this._pool) {
if (config.Logging.DB.type == 'mssql'){
const dbOptions = {
user: config.Logging.DB.user,
password: config.Logging.DB.password,
server: config.Logging.DB.mssql.server,
database: config.Logging.DB.mssql.database,
options: {
encrypt: config.Logging.DB.encrypt
}
};
this._pool = new mssql.ConnectionPool(dbOptions);
}
}
return this._pool;
}
insertHTTPRequest(req){
const pool = this.get_pool();
if (config.Logging.DB.type == 'mssql'){
if (pool._connected){
var request = new mssql.Request(pool);
var query = `INSERT INTO SD_LOG (
MODULE,
INSTANCE,
REMOTE_ADDR,
USERNAME,
USER_AGENT,
HTTP_METHOD,
HTTP_REQ_URL
) OUTPUT Inserted.ID_SD_LOG VALUES (
#module,
#instance,
#remote_addr,
#username,
#user_agent,
#http_method,
#http_req_url
)`;
request.input('module', 'tokenizer');
request.input('instance', config.Deployment.instance);
request.input('remote_addr', req.ip);
request.input('username', req.user.displayName);
request.input('user_agent', req.headers['user-agent']);
request.input('http_method', req.method);
request.input('http_req_url', req.url);
return request.query(query);
}else{
return pool.connect().then(() => {
var request = new mssql.Request(pool);
var query = `INSERT INTO SD_LOG (
MODULE,
INSTANCE,
REMOTE_ADDR,
USERNAME,
USER_AGENT,
HTTP_METHOD,
HTTP_REQ_URL
) OUTPUT Inserted.ID_SD_LOG VALUES (
#module,
#instance,
#remote_addr,
#username,
#user_agent,
#http_method,
#http_req_url
)`;
request.input('module', 'tokenizer');
request.input('instance', config.Deployment.instance);
request.input('remote_addr', req.ip);
request.input('username', req.user.displayName);
request.input('user_agent', req.headers['user-agent']);
request.input('http_method', req.method);
request.input('http_req_url', req.url);
request.query(query);
}
}
}
}
I am using a middleware in the routes to save the request into the DB, like this:
app.use(function(req, res, next){
//send req to DB, get ID_SD_LOG from DB, assign to req.id
db_instance.insertHTTPRequest(req).then((genid)=>{
req.id = genid;
next();
}).catch((err)=>{
combinedLogger.error(err);
res.send('Database is unavailable.');
res.end();
})
});
Thing is, I am getting an error, however, in console, the error is undefined. So I really can't figure out whats wrong. I can imagine it's the connect() method, as I tested logging in console static string in the db request and I don't them, which I assume it's not even accessing that part.
Any help?
Thanks!