I'm opening this issue because:

• npm is crashing.
• npm is producing an incorrect install.
• npm is doing something I don't understand.
• Other (see below for feature requests):

What's going wrong?

I have a postinstall step that runs bower install, which is necessary for my build to succeed in CI. However, CircleCI v2 runs containers as root, and the following warning gets thrown:

cannot run in wd %s %s (wd=%s) undefined bower install /root/project

In short, it seems as if npm is trying to drop to an unprivileged user and failing (I'm pretty sure this is separate from the fact bower will fail if run as a root user without the --allow-root flag).

All of this is fine and understandable (supplying --unsafe-perm to npm and --allow-root to bower fixes my issue), but npm should probably throw an error (instead of a warning) in the event of this happening so builds fail earlier.

How can the CLI team reproduce the problem?

There's no npm-debug.log file generated in this case.

1. Create a package.json with bower as a dependency and bower install as a postinstall script.
2. Run npm install as root.

supporting information:

• npm -v prints: 5.3.0
• node -v prints: v8.2.1
• npm config get registry prints:

npm info it worked if it ends with ok
npm info using npm@5.3.0
npm info using node@v8.2.1
https://registry.npmjs.org/
npm info ok

• Windows, OS X/macOS, or Linux?: Linux
• Network issues:
  • Geographic location where npm was run: London, UK
  • I use a proxy to connect to the npm registry.
  • I use a proxy to connect to the web.
  • I use a proxy when downloading Git repos.
  • I access the npm registry via a VPN
  • I don't use a proxy, but have limited or unreliable internet access.
• Container:
  • I develop using Vagrant on Windows.
  • I develop using Vagrant on OS X or Linux.
  • I develop / deploy using Docker.
  • I deploy to a PaaS (Triton, Heroku).