yarn is required to install this library with npm

Bug

Installing this package using npm throws this error:

npm ERR! prepareGitDep sh: yarn: command not found
npm ERR! prepareGitDep npm ERR! code ELIFECYCLE
npm ERR! prepareGitDep npm ERR! syscall spawn
npm ERR! prepareGitDep npm ERR! file sh
npm ERR! prepareGitDep npm ERR! errno ENOENT
npm ERR! prepareGitDep npm ERR! react-native-device-info@5.4.1 prepare: `yarn build`
npm ERR! prepareGitDep npm ERR! spawn ENOENT
npm ERR! prepareGitDep npm ERR!
npm ERR! prepareGitDep npm ERR! Failed at the react-native-device-info@5.4.1 prepare script.

It appears it expects yarn to be installed. If this is expected, it would be helpful if the documentation states as such. However, the docs state you can use either npm or yarn.

Environment info

React native info output:

System:
    OS: macOS Mojave 10.14.6
    CPU: (8) x64 Intel(R) Core(TM) i7-4980HQ CPU @ 2.80GHz
    Memory: 128.77 MB / 16.00 GB
    Shell: 3.2.57 - /bin/bash
  Binaries:
    Node: 10.16.0 - ~/.nvm/versions/node/v10.16.0/bin/node
    Yarn: 1.17.3 - ~/.nvm/versions/node/v10.16.0/bin/yarn
    npm: 6.9.0 - ~/.nvm/versions/node/v10.16.0/bin/npm
    Watchman: 4.9.0 - /usr/local/bin/watchman
  SDKs:
    iOS SDK:
      Platforms: iOS 13.2, DriverKit 19.0, macOS 10.15, tvOS 13.2, watchOS 6.1
    Android SDK:
      API Levels: 23, 25, 26, 27, 28, 29
      Build Tools: 28.0.2, 28.0.3, 29.0.0
      System Images: android-27 | Google APIs Intel x86 Atom, android-27 | Google Play Intel x86 Atom, android-28 | Google APIs Intel x86 Atom, android-28 | Google Play Intel x86 Atom, android-29 | Google Play Intel x86 Atom
  IDEs:
    Android Studio: 3.5 AI-191.8026.42.35.6010548
    Xcode: 11.3/11C29 - /usr/bin/xcodebuild
  npmPackages:
    react: ^16.9.0 => 16.12.0 
    react-native: ^0.61.5 => 0.61.5 
  npmGlobalPackages:
    react-native-cli: 2.0.1
    react-native: 0.59.10

Library version: 5.4.1

Steps To Reproduce

1. Ensure “yarn” is not installed
2. Run “npm i” on a project depending on this library. …

Describe what you expected to happen:

1. Installation completes successfully

Reproducible sample code

N/A

[twelve17]

For the record, I was not making a judgement call on yarn vs npm 😀

[mikehardy]

npm is packaged with node whereas yarn is optional, so at least for any path a normal user would take, yes, please PR away. I don’t like mixing dependency managers but I also prefer yarn personally (as do the other maintainers here) so for non-essential (i.e., maintainer-only commands) I think it’s a toss up. Probably should pick one and go with it (which would be npm I suppose. @Johan-dutoit what do you think? I’m inclined to just say “okay, it’s npm now” and move on, feels like it could turn into something like a whitespace debate otherwise, but maybe I’m missing something?