Npm not working after yarn install (cannot find number-is-nan)

Question

I installed yarn via brew to my macOS 10.13 and yarn works just fine. The problem occurs when i try to use npm. I get the following error on every command i try to run:

gregor-mbp:~ gregor$ npm -v
module.js:471
    throw err;
    ^

Error: Cannot find module 'number-is-nan'
    at Function.Module._resolveFilename (module.js:469:15)
    at Function.Module._load (module.js:417:25)
    at Module.require (module.js:497:17)
    at require (internal/module.js:20:19)
    at Object.<anonymous> (/usr/local/lib/node_modules/npm/node_modules/npmlog/node_modules/gauge/node_modules/string-width/node_modules/code-point-at/index.js:2:19)
    at Module._compile (module.js:570:32)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)

I tried to install this number-is-nan module as global via yarn but no success.

Now i have to install all packages and run scripts over yarn which is not bad but my projects have scripts which run other scripts via npm:

package.json example:

...
"scripts": {
  "start": "start-command",
  "build": "build-command",
  "development": "NODE_ENV=dev npm run build && npm run start",
  "production": "NODE_ENV=prod npm run build && npm run start"
},
...

And when i run yarn development i get the same error as above. While i'm only one in development team that has yarn installed i cannot change the configurations to yarn because others use npm.

So i there any solution to this, so yarn and npm could co-exist on same system without errors? Or should i just delete yarn?

Answer 1

Try to use yarn to reinstall npm:

yarn global add npm