Why I'm always getting an Internal Server Error (code 500) after making a request to BackEnd - mysql

Question

I'm having a little trouble with my site and I can't understand what is happening.
First of all I have to say that I was NOT having this behavior when developing on localhost, but now that my site is close to be completed I think that uploading my code to a hosting service and make some tests there would be a good idea.
The issue is that when I make a request to the database, most of the times the site keeps in an eternal loading state, until the error code 500: Internal Server Error appears (I said "most of the times" because it works nice sometime, but normally it remains in a pending state).
Given the fact that SOME TIMES the request work nice, makes me think that the issue is not on the server.js file (where I defined the endpoints), and also is not on my controllers files (where I have some logic and the requests itself).
I'll leave here some pics as example of what is happening but if you need some extra info just tell me:
A simple login example, I just fill the fields and send the request
And here you can see how the request remain as pending
Until it fails
EDIT: I'm using package Mysql2 to connect to the DB, and I was reading that this behavior may be because a bad use of connections (and I'm reading about "pools", but I'm kinda lost tbh)
Here is the connection file:
require("dotenv").config();
const mysql = require("mysql2");
const db = mysql.createConnection({
host: process.env.DB_HOST,
user: process.env.DB_USER,
password: process.env.DB_PASSWORD,
database: process.env.DB_NAME,
waitForConnections: true,
});
const connection = async () => {
db.connect((err) => {
if (err) throw err;
console.log("Successfully connected");
})
}
exports.db = db;
exports.connection = connection;
The first call to the DB (just to check the connection)
connection().then(() => {
app.listen(port, () => {
console.log(`Server running at ...`);
});
});
And the login logic
app.post("/dev-end/api/login", async (req, res) => {
await singleAccount(db, req.body.email)
.then(async (response) => {
if (response.code) {
res.render("templateLogin");
}
try {
if (await bcrypt.compare(req.body.password, response.password)) {
const user = { id: response._id, name: response.name };
await deleteTokenById(db, user.id.toString());
const accessToken = generateAccessToken(user);
const refreshToken = jwt.sign(
user,
process.env.REFRESH_TOKEN_SECRET,
{ expiresIn: "604800s" }
);
createToken(db, {
_id: user.id,
accessToken: accessToken,
refreshToken: refreshToken,
createdAt: new Date().toISOString().slice(0, 19).replace("T", " "),
}).then(
res
.cookie("access_token", accessToken, {
httpOnly: true,
maxAge: 60000 * 60 * 24 * 7,
})
.redirect("/dev-end/dashboard")
);
} else {
res.render("templateLogin");
}
} catch {
res.status(500).send();
}
})
.catch(console.log);
});
=>=>=>=>=>=>=>=>=>=>=>=>=>=>=>=>
const singleAccount = async (conn, email) => {
return await read(conn).then((res) => {
if (!res.code) {
const result = res.find((e) => e.email.toString() === email);
if (!result) {
return {
code: 404,
msg: "No account was found with the provided id",
};
}
return result;
}
return res;
});
};
=>=>=>=>=>=>=>=>=>=>=>=>=>=>=>=>
const read = async (conn) => {
const sql = `SELECT * FROM accounts`;
return await conn.promise().query(sql)
.then(([res, fields]) => res);
};