webpack - Unable to run `npm install` in fresh Phoenix project on Powershell windows

Question

Background

I am trying to do a Phoenix LiveView project to learn how it works. To this extent, I have, in my windows 10 machine, installed Elixir and NPM via chocolatey. I have also successfully run the commands:

$ mix archive.install hex phx_new
$ mix phx.new demo --live

Problem

The problem comes after running the second command. After its completion I am told to follow some additional steps:

We are almost there! The following steps are missing:

    $ cd test_app
    $ cd assets && npm install && node node_modules/webpack/bin/webpack.js --mode development

In specific, the npm install part fails:

> npm install
npm ERR! code ERESOLVE
npm ERR! ERESOLVE unable to resolve dependency tree
npm ERR!
npm ERR! Found: [email protected]
npm ERR! node_modules/webpack
npm ERR!   dev webpack@"4.41.5" from the root project
npm ERR!   peer webpack@">=2" from [email protected]
npm ERR!   node_modules/babel-loader
npm ERR!     dev babel-loader@"^8.0.0" from the root project
npm ERR!   3 more (copy-webpack-plugin, css-loader, hard-source-webpack-plugin)
npm ERR!
npm ERR! Could not resolve dependency:
npm ERR! dev mini-css-extract-plugin@"^0.9.0" from the root project
npm ERR!
npm ERR! Conflicting peer dependency: [email protected]
npm ERR! node_modules/webpack
npm ERR!   peer webpack@"^4.4.0" from [email protected]
npm ERR!   node_modules/mini-css-extract-plugin
npm ERR!
npm ERR! Fix the upstream dependency conflict, or retry
npm ERR! this command with --force, or --legacy-peer-deps
npm ERR! to accept an incorrect (and potentially broken) dependency resolution.
npm ERR!
npm ERR! See C:UsersuserAppDataLocal
pm-cacheeresolve-report.txt for a full report.

npm ERR! A complete log of this run can be found in:
npm ERR!     C:UsersuserAppDataLocal
pm-cache\_logs2021-01-29T08_41_13_010Z-debug.log

This is a fresh project. I am confused as to why this is even happening. If I run npm install --force then I am greeted with a wall of errors, I assume because of this issue.

Question

How can I fix this?

question from:https://stackoverflow.com/questions/65951347/unable-to-run-npm-install-in-fresh-phoenix-project-on-powershell-windows

Answer 1

The issue here was the node-sass version. There is currently a bug with Node 15 and that package.

https://elixirforum.com/t/unable-to-run-npm-install-in-fresh-phoenix-project-on-powershell-windows/37164/4?u=fl4m3ph03n1x

The issue can be fixed by using the command:

npm i --legacy-peer-deps