Path issue on windows using NVM to manage node, "ERROR: Cannot find npm binary"

[evelant]

Describe The Bug:
When using nvm on windows logs show "ERROR: Cannot find npm binary"

I think this is due to this function here https://github.com/oznu/homebridge-config-ui-x/blob/45a49188e2cadf52857314bb8620d594e1bb6cc7/src/modules/plugins/plugins.service.ts#L639

It checks a couple set paths on windows but does not check the $PATH environment variable. When using NVM the node/npm installation is on the path but not at any of the fixed locations checked by that function. I think this could be quickly resolved by also just checking if npm is on the path when using windows.

To Reproduce:
Install node via nvm windows, install homebridge-config-ui-x and service. Run it and see this error in the logs.

Expected behavior:
homebridge-config-ui-x should always check the path for binaries, even on windows.

Logs:

https://github.com/oznu/homebridge-config-ui-x/blob/45a49188e2cadf52857314bb8620d594e1bb6cc7/src/modules/plugins/plugins.service.ts#L639

Homebridge Config:

N/A

Screenshots:
N/A

Environment:

• Node.js Version: 12.18.3
• NPM Version: 6.14.6
• Homebridge Version: 1.2.2
• Homebridge Config UI X Version: 4.27.1
• Operating System: Windows
• Process Supervisor: none

[evelant]

I tried to build locally to make a fix for a PR but I couldn't get config-ui-x to build on windows with the instructions in CONTRIBUTING.MD

There are two ways to fix this that I see, one is

npm install --save command-exists

plugins.service.ts

import { sync as commandExistsSync } from 'command-exists';

....
 /**
   * Helper function to work out where npm is
   */
  private getNpmPath() {
    // Check if npm is on the path, regardless of system
    if(commandExistsSync('npm')){
      const npmPath = ['npm'];
      if (os.platform() === 'win32'){
        // Add global if on Windows
        npmPath.push('-g');
      }
      return npmPath;
    }

    if (os.platform() === 'win32') {

      // if npm not on path and running on windows find the full path to npm in some common locations
      const windowsNpmPath = [
        path.join(process.env.APPDATA, 'npm/npm.cmd'),
        path.join(process.env.ProgramFiles, 'nodejs/npm.cmd'),
      ]
        .filter(fs.existsSync);

      if (windowsNpmPath.length) {
        return [windowsNpmPath[0], '-g'];
      } else {
        this.logger.error(`ERROR: Cannot find npm binary. You will not be able to manage plugins or update homebridge.`);
        this.logger.error(`ERROR: You might be able to fix this problem by running: npm install -g npm`);
      }

    }
    // Fallback if commandExistsSync somehow didn't find it, Linux and macOS don't require the full path to npm
    return ['npm'];
  }

OR

add NVM_SYMLINK to the windows paths searched

plugins.service.ts

 // if npm not on path and running on windows find the full path to npm in some common locations
      const windowsNpmPath = [
        path.join(process.env.APPDATA, 'npm/npm.cmd'),
        path.join(process.env.ProgramFiles, 'nodejs/npm.cmd'),
        path.join(process.env.NVM_SYMLINK, 'npm.cmd'),
      ]
        .filter(fs.existsSync);

[evelant]

I worked around the issue for now with a symlink, from an administrator cmd prompt mklink /J "C:\Program Files\nodejs" C:\path\to\nvm\nodejs

[oznu]

Thanks, fixed with the NVM_SYMLINK solution.