Why does "ffmpeg exited with code 1: concat:file0.mp3: Invalid argument" error occur?

Question

fmpeg

Hello! I'm making a telegram bot that converts text to speech using ffmpeg. When I send him the second text for conversion, he breaks down, the first time he works fine. Tell me, please, what could be the problem?
The code:

const googleTTS = require('google-tts-api'); // CommonJS
const https = require('https');
const fs = require('fs');
const { Telegraf } = require('telegraf');
const bot = new Telegraf('Token')
const audioconcat = require('audioconcat');

bot.command("audio", (ctx) => {
    return ctx.replyWithAudio({ source: "./file.mp3" });
});

bot.on('message', (msg) => {
    const url = googleTTS.getAllAudioUrls(msg.update.message.text, {
        lang: 'ru',
      slow: false,
      host: 'https://translate.google.com',
      splitPunct: ',.?'
    });

    for (let i = 0; i < url.length; i++){
        const file = fs.createWriteStream("file" + i + ".mp3");
        const request = https.get(url[i].url, function(response) {
            response.pipe(file);
        });
    }

        let songs = [];
        
        for (let i = 0; i < url.length; i++){
            songs.push("file" + i + ".mp3");
        }

          audioconcat(songs)
            .concat('merged.mp3')

        songs = [];

    setTimeout(() => {
        msg.replyWithAudio({ source: "./merged.mp3" });
        songs = [];
    }, 2000);

})

bot.launch();

process.on('uncaughtException', function (err) {
    console.log(err);
});

Mistake:

events.js:291
      throw er; // Unhandled 'error' event
      ^

Error: ffmpeg exited with code 1: concat:file0.mp3: Invalid argument

    at ChildProcess.<anonymous> (/home/pefbrute/Desktop/Offline-syntheser/node_modules/fluent-ffmpeg/lib/processor.js:182:22)
    at ChildProcess.emit (events.js:314:20)
    at Process.ChildProcess._handle.onexit (internal/child_process.js:275:12)
Emitted 'error' event on FfmpegCommand instance at:
    at emitEnd (/home/pefbrute/Desktop/Offline-syntheser/node_modules/fluent-ffmpeg/lib/processor.js:424:16)
    at endCB (/home/pefbrute/Desktop/Offline-syntheser/node_modules/fluent-ffmpeg/lib/processor.js:544:13)
    at handleExit (/home/pefbrute/Desktop/Offline-syntheser/node_modules/fluent-ffmpeg/lib/processor.js:170:11)
    at Socket.<anonymous> (/home/pefbrute/Desktop/Offline-syntheser/node_modules/fluent-ffmpeg/lib/processor.js:197:11)
    at Socket.emit (events.js:326:22)
    at Pipe.<anonymous> (net.js:676:12)

Answer 1

Corrected the code (added a couple of timeouts) and now everything works!

const googleTTS = require('google-tts-api'); // CommonJS
const https = require('https');
const fs = require('fs');
const { Telegraf } = require('telegraf');
const bot = new Telegraf('TOKEN')
const audioconcat = require('audioconcat');

bot.command("audio", (ctx) => {
    return ctx.replyWithAudio({ source: "./file.mp3" });
});

bot.on('message', (msg) => {
    const url = googleTTS.getAllAudioUrls(msg.update.message.text, {
        lang: 'ru',
      slow: false,
      host: 'https://translate.google.com',
      splitPunct: ',.?'
    });

    for (let i = 0; i < url.length; i++){
        const file = fs.createWriteStream("file" + i + ".mp3");
        const request = https.get(url[i].url, function(response) {
            response.pipe(file);
        }); 
    }

    setTimeout(() => {
        let songs = [];
            for (let i = 0; i < url.length; i++){
                songs.push("./file" + i + ".mp3");
            }
            // console.log(songs);
            audioconcat(songs)
            .concat('merged.mp3')
        }, 3000);

    setTimeout(() => {
        msg.replyWithAudio({ source: "./merged.mp3" });
        songs = [];
    }, 4000);

})

bot.launch();

process.on('uncaughtException', function (err) {
    console.log(err);
});