Why does this code sometimes work but 95% of the time it doesnt.

import * as wmill from "windmill-client"
import { Client } from "pg"
import { from as copyFrom } from "pg-copy-streams"

// Defining the type for Postgres resource
type Postgresql = {
  host: string,
  port: number,
  user: string,
  dbname: string,
  sslmode: string,
  password: string,
  root_certificate_pem: string
}

export async function  main(csvFile: string, postgresqlResource: Postgresql) {

  //Start up db connection
  //Creating a new postgres client
  const client = new Client({
    user: postgresqlResource.user,
    database: postgresqlResource.dbname,
    password: postgresqlResource.password,
    host: postgresqlResource.host, // Changed from hostname to host
    port: postgresqlResource.port
  });

let stream;
const time = new Date().toISOString();


  try {
    await client.connect();

    //test to make sure connection is working.
    //await client.query("INSERT INTO inventory (sku,warehouse_id,time,qty) VALUES ('test',2,now(),25)");


    stream = await client.query(copyFrom('COPY inventory (sku,warehouse_id,time,qty) FROM STDIN'));

    let numOfRows = 0;   

    stream.write('partnumber' + '\t' + '2' + '\t' + time + '\t' + '43' + '\n');
    //await stream.end();
    
  }
  catch (e)
  {
    console.log(e);
  }
  finally
  {
    stream.end();  
  }