Where is NPM config file?

I edited the npm config file with npm edit config. I made a syntax error in it and saved the file. Now, no matter what I try with npm, it will complain about it. I know what the syntax is and I would like to fix it, but I can't find the file anywhere.

C:\Users\Arthur>npm
Error: Failed parsing JSON config key cache: "C:\Users\Le Roi Arthur\AppData\Roaming\npm-cache"
    at parseField (D:\nodejs\node_modules\npm\lib\config\core.js:376:13)
    at D:\nodejs\node_modules\npm\lib\config\core.js:330:24
    at Array.forEach (<anonymous>)
    at Conf.add (D:\nodejs\node_modules\npm\lib\config\core.js:328:23)
    at ConfigChain.addString (D:\nodejs\node_modules\npm\node_modules\config-chain\index.js:244:8)
    at Conf.<anonymous> (D:\nodejs\node_modules\npm\lib\config\core.js:316:10)
    at D:\nodejs\node_modules\npm\node_modules\graceful-fs\graceful-fs.js:90:16
    at FSReqWrap.readFileAfterClose [as oncomplete] (internal/fs/read_file_context.js:53:3)
TypeError: Cannot read property 'loaded' of undefined
    at exit (D:\nodejs\node_modules\npm\lib\utils\error-handler.js:98:27)
    at errorHandler (D:\nodejs\node_modules\npm\lib\utils\error-handler.js:216:3)
    at D:\nodejs\node_modules\npm\bin\npm-cli.js:77:20
    at cb (D:\nodejs\node_modules\npm\lib\npm.js:225:22)
    at D:\nodejs\node_modules\npm\lib\npm.js:263:24
    at D:\nodejs\node_modules\npm\lib\config\core.js:83:7
    at Array.forEach (<anonymous>)
    at Conf.<anonymous> (D:\nodejs\node_modules\npm\lib\config\core.js:82:13)
    at Conf.f (D:\nodejs\node_modules\npm\node_modules\once\once.js:25:25)
    at Object.onceWrapper (events.js:286:20)
D:\nodejs\node_modules\npm\lib\utils\error-handler.js:98
  var doExit = npm.config.loaded ? npm.config.get('_exit') : true
                          ^

TypeError: Cannot read property 'loaded' of undefined
    at exit (D:\nodejs\node_modules\npm\lib\utils\error-handler.js:98:27)
    at process.errorHandler (D:\nodejs\node_modules\npm\lib\utils\error-handler.js:216:3)
    at process.emit (events.js:198:13)
    at process._fatalException (internal/bootstrap/node.js:496:27)
Error: Failed parsing JSON config key cache: "C:\Users\Le Roi Arthur\AppData\Roaming\npm-cache"
    at parseField (D:\nodejs\node_modules\npm\lib\config\core.js:376:13)
    at D:\nodejs\node_modules\npm\lib\config\core.js:330:24
    at Array.forEach (<anonymous>)
    at Conf.add (D:\nodejs\node_modules\npm\lib\config\core.js:328:23)
    at ConfigChain.addString (D:\nodejs\node_modules\npm\node_modules\config-chain\index.js:244:8)
    at Conf.<anonymous> (D:\nodejs\node_modules\npm\lib\config\core.js:316:10)
    at D:\nodejs\node_modules\npm\node_modules\graceful-fs\graceful-fs.js:90:16
    at FSReqWrap.readFileAfterClose [as oncomplete] (internal/fs/read_file_context.js:53:3)
TypeError: Cannot read property 'loaded' of undefined
    at exit (D:\nodejs\node_modules\npm\lib\utils\error-handler.js:98:27)
    at errorHandler (D:\nodejs\node_modules\npm\lib\utils\error-handler.js:216:3)
    at D:\nodejs\node_modules\npm\bin\npm-cli.js:77:20
    at cb (D:\nodejs\node_modules\npm\lib\npm.js:225:22)
    at D:\nodejs\node_modules\npm\lib\npm.js:263:24
    at D:\nodejs\node_modules\npm\lib\config\core.js:83:7
    at Array.forEach (<anonymous>)
    at Conf.<anonymous> (D:\nodejs\node_modules\npm\lib\config\core.js:82:13)
    at Conf.f (D:\nodejs\node_modules\npm\node_modules\once\once.js:25:25)
    at Object.onceWrapper (events.js:286:20)
D:\nodejs\node_modules\npm\lib\utils\error-handler.js:98
  var doExit = npm.config.loaded ? npm.config.get('_exit') : true
                          ^

TypeError: Cannot read property 'loaded' of undefined
    at exit (D:\nodejs\node_modules\npm\lib\utils\error-handler.js:98:27)
    at process.errorHandler (D:\nodejs\node_modules\npm\lib\utils\error-handler.js:216:3)
    at process.emit (events.js:198:13)
    at process._fatalException (internal/bootstrap/node.js:496:27)

Uninstalling and re-installing nodeJS doesn't fix the issue, the file is stored in cache somewhere. It's infuriately frustrating how hard it is to put my hands on that file.

Where can I find the npm config file ?

You need to edit npmrc file, take a look at documentation it will help you to find the appropriate one.

The four relevant files are:

• Per-project config file: /path/to/my/project/.npmrc
• Per-user config file: ~/.npmrc
• Global config file: $PREFIX/npmrc
• Built-in npm config file: /path/to/npm/npmrc