Node.js Connection terminated before query is finished

Newbie with node.js.
I have set up an Node/express server on a Windows Server hosting a PostgreSQL database.
My goal is to insert in the database the data from a csv file choosen by a user on its own computer, using a HTML form.

Here is the part of the js file executed after the user submits the form:

app.post('/envoi', upload.single("fichiercsv"), async(req, res) => {
let newClient
try {
const { identifiant, motdepasse } = req.body
const clientConfigModifie = {
...clientConfigDefaut,
user: identifiant,
password: ''
}
newClient = new Client(clientConfigModifie)
await newClient.connect()
const rows = []
const buffer = req.file.buffer
// console.log(buffer) //ok
const readableStreamFromBuffer = new stream.Readable()
readableStreamFromBuffer.push(req.file.buffer)
readableStreamFromBuffer.push(null)
await new Promise( (resolve, reject) => {
fastcsv.parseStream(readableStreamFromBuffer, { headers: false })
.on('data', us => {
rows.push(us)	
})
.on('end', async() => { 
rows.shift()
const usTotal = rows.map( us => us.join("").split(";"))
// console.log(us)
for (const us of usTotal) {
await newClient.query("insert into activite.us (numus, gidgeo) VALUES ($1, $2)", [us[0], us[13]])
})
resolve()
})
.on("error", error => console.error(error))
})	
}	
catch(e) {
console.log("erreur lors du traitement", e)
res.send(`<h3>échec de la connexion</h3>`)
}
finally {
try {
newClient.end()
}
catch(e) { 
console.log(e) 
}
}
})

• If I omit the finally part, the data are inserted in the database, but the connection is running...
• With the finally part, only the first row of us is inserted. Thus, I have the message :

error: Connection terminated at C:\Apache\balbla\

In this case, it seems that newClient.query runs one time only then for some reason the connection is terminated but not ended.
What am I doing wrong ?

EDIT : code updated after @I2yscho answer.

Problem is you don't handle insert operations asynchronously. This code is not a best way how to handle this, but it is working solution. I recommend you to use some sort of bulk insert in one query.

.on('end', () => {
rows.shift();
const usData = rows.map(us => us.join("").split(";"));
const insertPromises = usData.map(us => {
return newClient.query("INSERT INTO activite.us (numus, gidgeo) VALUES ($1, $2)", [us[0], us[13]]);
});
Promise.all(insertPromises)
.then(() => {
resolve();
})
.catch(error => {
reject(error);
});
})