title: Cordova can't add plugin: Error: Cannot find module 'unorm'
body: <p>I'm trying to add a plugin to my cordova app, but I get an error saying "The platform "ios" does not appear to be a valid cordova platform. It is missing API.js. ios not supported."</p>
  
  <pre><code>node --version
  v9.2.0
  
  cordova --version
  8.0.0
  </code></pre>
  
  <p>Here is the command I'm running</p>
  
  <pre><code>cordova plugin add cordova-plugin-appinfo
  </code></pre>
  
  <p>And the complete output:</p>
  
  <pre><code>Installing "cordova-plugin-appinfo" for ios
  Unable to load PlatformApi from platform. Error: Cannot find module 'unorm'
  Failed to install 'cordova-plugin-appinfo': Error [ERR_UNHANDLED_ERROR]: Unhandled error. (The platform "ios" does not appear to be a valid cordova platform. It is missing API.js. ios not supported.)
      at EventEmitter.emit (events.js:140:19)
      at EventEmitter.module.exports.emit (/Users/james/.nvm/versions/node/v9.2.0/lib/node_modules/cordova/node_modules/cordova-common/src/events.js:71:17)
      at Object.getPlatformApiFunction (/Users/james/.nvm/versions/node/v9.2.0/lib/node_modules/cordova/node_modules/cordova-lib/src/cordova/util.js:499:20)
      at Object.getPlatformApi (/Users/james/.nvm/versions/node/v9.2.0/lib/node_modules/cordova/node_modules/cordova-lib/src/platforms/platforms.js:55:25)
      at handleInstall (/Users/james/.nvm/versions/node/v9.2.0/lib/node_modules/cordova/node_modules/cordova-lib/src/plugman/install.js:593:29)
      at /Users/james/.nvm/versions/node/v9.2.0/lib/node_modules/cordova/node_modules/cordova-lib/src/plugman/install.js:357:28
      at _fulfilled (/Users/james/.nvm/versions/node/v9.2.0/lib/node_modules/cordova/node_modules/cordova-lib/node_modules/q/q.js:787:54)
      at self.promiseDispatch.done (/Users/james/.nvm/versions/node/v9.2.0/lib/node_modules/cordova/node_modules/cordova-lib/node_modules/q/q.js:816:30)
      at Promise.promise.promiseDispatch (/Users/james/.nvm/versions/node/v9.2.0/lib/node_modules/cordova/node_modules/cordova-lib/node_modules/q/q.js:749:13)
      at /Users/james/.nvm/versions/node/v9.2.0/lib/node_modules/cordova/node_modules/cordova-lib/node_modules/q/q.js:509:49
  (node:35697) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): Unhandled error. (The platform "ios" does not appear to be a valid cordova platform. It is missing API.js. ios not supported.)
  (node:35697) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
  </code></pre>
  
  <p>I'm certain this is a valid Cordova project and the iOS platform seems to work fine (I can build and run on an iPhone).</p>