ENOENT every time I put a function inside an express.js server - node.js

Question

I'm trying to build a simple wrapper for the tesseract.js API so I can use it with a simple GET request within Google Apps Script and I'm having some trouble. For some reason it works perfectly but as soon as I put the same code inside of the express server I keep getting this:
Error: ENOENT: no such file or directory, open
Here's the code:
const Tesseract = require('tesseract.js')
const request = require('request')
const fs = require('fs')
require('custom-env').env();
const express = require('express');
const app = express();
const os = require('os');
const path = require('path');
const PORT = process.env.PORT;
const url = 'http://tesseract.projectnaptha.com/img/eng_bw.png'
app.get('/', function(req, res){
if (req.query.imageUrl) {
const filename = 'pic.png'
const tempFilePath = path.join(os.tmpdir(), 'pic.png');
const writeFile = fs.createWriteStream(tempFilePath);
console.log('got here');
request(url).pipe(writeFile).on('close', function() {
console.log(url, 'saved to', tempFilePath)
Tesseract.recognize(tempFilePath)
.progress(function (p) {})
.catch(err => console.error(err))
.then(function (result) {
res.send(result.text);
process.exit(0);
})
});
fs.unlinkSync(tempFilePath);
} else {
res.send('Send a URL you muppet!');
}
});

Answer 1

Tesseract.recognize is async and returns a promise. Yet you are calling fs.unlinkSync(tempFilePath); immediately after recognize() which will execute before recognize() completes. This race can mean the file is killed before you are done processing.
You should remove the unlink into the then so that you only unlink when complete.
app.get('/', function(req, res){
if (req.query.imageUrl) {
const filename = 'pic.png'
const tempFilePath = path.join(os.tmpdir(), 'pic.png');
const writeFile = fs.createWriteStream(tempFilePath);
console.log('got here');
request(url).pipe(writeFile).on('close', function() {
console.log(url, 'saved to', tempFilePath)
Tesseract.recognize(tempFilePath)
.progress(function (p) {})
.catch(err => console.error(err))
.then(function (result) {
res.send(result.text);
fs.unlinkSync(tempFilePath);
})
});
} else {
res.send('Send a URL you muppet!');
}
});