npm ERR! `unsafe-perm` is not a valid npm option

[Loïc Minier]

Hi,

The npm plugin runs:
  npm config set unsafe-perm true
during builds; this is not supported in recent npms and causes an error:
2023-04-08 16:55:43.386 :: 2023-04-08 16:55:41.117 :: + tar xzf - -C /root/parts/hello-node/install/ --no-same-owner --strip-components=1
2023-04-08 16:55:43.386 :: 2023-04-08 16:55:42.622 :: + npm config set unsafe-perm true
2023-04-08 16:55:43.386 :: 2023-04-08 16:55:42.882 :: npm ERR! `unsafe-perm` is not a valid npm option
2023-04-08 16:55:43.386 :: 2023-04-08 16:55:42.883 ::
2023-04-08 16:55:43.386 :: 2023-04-08 16:55:42.883 :: npm ERR! A complete log of this run can be found in:
2023-04-08 16:55:43.386 :: 2023-04-08 16:55:42.883 :: npm ERR! /root/.npm/_logs/2023-04-08T16_55_42_865Z-debug-0.log

This can be reproduced with a snapcraft.yaml such as:
=====
name: hello-node
base: core22
version: '1.0'
summary: Whatever
description: Whatever
grade: devel
confinement: devmode

parts:
  hello-node:
    plugin: npm
    source: src
    npm-include-node: true
    npm-node-version: 18.15.0
=====

With node-version 16.15.0, the build works; with node-version 18.15.0 it fails. 18.15.0 is the current upstream LTS node version, while the latest release is 19.8.1.

Here's a git repo with a sample hello world nodejs/npm snap:
https://github.com/lool/hello-node-snap

Best,