Spawn child_process to run Python script using Nodejs not working in Heroku but works locally

Question

Hi I am running Nodejs and I need to pass two input variables from a webpage into a Python script this all works well locally but when I deploy to heroku it looks like the python script is not being run. In the logs I see see 'child process close all stdio with code 1'

Logs:

2022-04-21T10:16:35.439296Z app[web.1]: req.body.Input_path: test value 1

2022-04-21T10:16:35.439334Z app[web.1]: req.body.Output_path: test value 2

2022-04-21T10:16:35.438866Z system[router]: at=info method=POST path="/wrapper" host="conversionnodeapp.factset.io" fwd="xxx" zone=a container=web.1 connect=8ms service=95ms status=200 bytes=0 protocol=https tls_version=tls1.3 request_id=3f4a4bc5-63b0-4804-a291-83dd991a0fb3

2022-04-21T10:16:35.466844Z app[web.1]: child process close all stdio with code 1

My index.js code:

const express = require('express')
const {spawn} = require('child_process');
const { join } = require('path');
const app = express()
const PORT = process.env.PORT || 5000

app.use(express.json())

app.use(express.static(join(__dirname, 'public')));

app.get('/', (req, res) => {
    res.sendFile(join(__dirname, "index.html"));
});



app.post('/wrapper', (req, res) => {
    console.log(`req.body.Input_path: ${req.body.Input_path}`),
    console.log(`req.body.Output_path: ${req.body.Output_path}`)
 
 var dataToSend;
 // spawn new child process to call the python script
 const python = spawn('python', ['wrapper.py']);

 python.stdout.on('data', function (data) {
  console.log('Pipe data from python script ...');
  dataToSend = data.toString();
  console.log(data)
 });

 python.on('close', (code) => {
 console.log(`child process close all stdio with code ${code}`);
 // send data to browser
 res.send(dataToSend)
 });
 
})
app.listen(PORT, () => console.log(`Example app listening on port 
${PORT}!`))

Any help would be appreciated or if there is a better way to run a Python script from a webpage passing two variables.

P.S I am working in a network support role but want to create internal tools to help the team and learn some code along the way.

Many thanks