I am trying to download a requested file from the frontend to a backend server with nodejs. To do it in react I use axios and in nodejs I am using express. The problem is that with my implementation I get the following error:

Error [ERR_STREAM_CANNOT_PIPE]: Cannot pipe, not readable
    at new NodeError (node:internal/errors:371:5)
    at ServerResponse.pipe (node:_http_outgoing:987:22)
    at file:///home/marc/Disco/Projects/GymApp/server/routes/trainer.js:249:9
    at processTicksAndRejections (node:internal/process/task_queues:96:5)
Emitted 'error' event on ServerResponse instance at:
    at ServerResponse.pipe (node:_http_outgoing:987:8)
    at file:///home/marc/Disco/Projects/GymApp/server/routes/trainer.js:249:9
    at processTicksAndRejections (node:internal/process/task_queues:96:5) {
  code: 'ERR_STREAM_CANNOT_PIPE'

Here is the axios request:

const downloadTraining = async (id) => {
    const JWT = new ClassJWT();
    const axiosReq = axios.create();
    await JWT.checkJWT();
    axiosReq
      .post(`${serverPath}/download-training`, {
        trainer_id: await JWT.getId(),
        training_id: id,
        token: JWT.getToken(),
      })
      .then((res) => {
        console.log(res);
      })
      .catch((err) => console.log(err));
  }

Here I don't know what to do for the browser to download the file, if anyone know it, let me know.

Here is the nodejs code with express that gives me the error that I mentioned above:

import express from "express";
import { verifyJWT } from "../services/tokens/verifyJWT.js";
import Training from "../models/Training.js";
import fs from "fs";

const path = "/home/marc/Disco/Projects/AtlasFitness/";
const dirname = "uploads/trainings/";

routerTrainer.post("/download-training", verifyJWT, async (req, res) => {
  const { trainer_id, training_id } = req.body;
  let training = await Training.findOne({
    where: { id: training_id, trainer_id },
  });

  if (training) {
    const filePath = fs.createWriteStream(`${path}${dirname}${training.file_id}`);
    res.pipe(filePath);
    filePath.on('finish',() => {
        filePath.close();
        console.log('Download Completed'); 
    })
  }
})

Here is when I get the error, if anyone know how to fix it to get the file downloaded to the user's computer, please let me know it.