Bail out gracefully when running inside Yarn?

[Jürg Lehni]

I am not sure if this is possible, but I had this problem here with http://paperjs.org/ where I am using npm-force-resolutions to work around issues with Gulp 3 on recent Node versions:

paperjs/paper.js#1831

But when installing paper with yarn, this now fails in the preinstall step.

Since Yarn natively supports resolutions, the current fix is to use if-env to only run the command if npm is used, but maybe npm-force-resolutions could do this internally?

"preinstall": "if-env npm_config_heading=npm && npx npm-force-resolutions"

[Nathan Vogel]

On Windows, if I use PowerShell (VSCode's default terminal) and try to install via yarn I get this:

error D:\dev\node_modules\paper: Command failed.
Exit code: 1
Command: [[ $npm_config_heading == 'npm' ]] && npx npm-force-resolutions || true
Arguments:
Directory: D:\dev\node_modules\paper
Output:
'[[' is not recognized as an internal or external command,
operable program or batch file.
'true' is not recognized as an internal or external command,
operable program or batch file.

Using git's terminal works :)