Problems with API upon setting up Express JS on my ReactJS project - node.js

Question

I am working on a little project here and I ran into an issue after hooking up "register" and "login".
I did this through NodeJS with Express.
The error I am having is:
Access to XMLHttpRequest at 'api' from origin 'http://localhost:3000' has been blocked by CORS policy: The value of the 'Access-Control-Allow-Origin' header in the response must not be the wildcard '*' when the request's credentials mode is 'include'. The credentials mode of requests initiated by the XMLHttpRequest is controlled by the withCredentials attribute.
That appears in the console whenever I try to fetch the products from the API. I do not get this error if I haven't logged in to an account, but if I have logged in to an account that happens.
Here is my Nodejs code:
const express = require("express");
const mysql = require("mysql");
const cors = require("cors");
const bodyParser = require("body-parser");
const cookieParser = require("cookie-parser");
const session = require("express-session");
const bcrypt = require("bcrypt");
const saltRounds = 10;
const app = express();
app.use(
cors({
origin: ["http://localhost:3000"],
methods: ["GET", "POST"],
credentials: true,
})
);
app.use(cookieParser());
app.use(bodyParser.urlencoded({ extended: true }));
app.use(
session({
key: "",
secret: "",
resave: false,
saveUninitialized: false,
cookie: {
expires: 60 * 60 * 24,
},
})
);
app.use(express.json());
const db = mysql.createConnection({
user: "",
host: "",
password: "",
database: "",
});
app.post("/register", (req, res) => {
const firstName = req.body.firstName;
const lastName = req.body.lastName;
const username = req.body.username;
const phone = req.body.phone;
const password = req.body.password;
const email = req.body.email;
bcrypt.hash(password, saltRounds, (err, hash) => {
db.query(
"INSERT INTO `accounts`(`firstName`, `lastName`, `username`, `password`, `email`, `phone`) VALUES (?,?,?,?,?,?)",
[firstName, lastName, username, hash, email, phone],
(err, result) => {
console.log(err);
console.log(result);
}
);
});
});
app.get("/login", (req, res) => {
if (req.session.user) {
res.send({ loggedIn: true, user: req.session.user });
} else {
res.send({ loggedIn: false });
}
});
app.post("/login", (req, res) => {
const email = req.body.email;
const password = req.body.password;
let sql = `SELECT * FROM accounts WHERE email="${email}"`;
db.query(sql, (err, result) => {
try {
bcrypt.compare(password, result[0].password, (err, compResult) => {
if (err) throw err;
if (compResult) {
req.session.user = result;
res.send(compResult);
} else if (!compResult) {
res.send({ message: "Incorrect Password or Email!" });
}
});
} catch (err) {
res.send({ message: "Email does not exist!" });
}
});
});
Let me know if there is anything else you need!