Installing plugins keeps failing because of es6-prepare-plugin - ios

Question

I am trying to prepare my iOS app and I need to get socialsharing and the whitelist plugin working, but they do not work. For example, when I do this:
sudo cordova plugin add cordova-plugin-x-socialsharing
I get this:
Installing "cordova-plugin-x-socialsharing" for android
Failed to install 'cordova-plugin-x-socialsharing':
CordovaError:
Failed to fetch plugin es6-promise-plugin via registry. Probably this
is either a connection problem, or plugin spec is incorrect. Check
your connection and plugin name/version/URL. Error: npm: Command
failed with exit code 1 Error output: npm ERR! code ENOLOCAL npm ERR!
Could not install from "node_modules/es6-promise-plugin" as it does
not contain a package.json file.
npm ERR!
How can I fix this? I tried everything. From sudo to non-sudo commands, but nothing is working for me. Adding es6-prepare-plugin manually does not work either.
My system information:
Cordova CLI: 7.0.1
Gulp version: CLI version 3.9.1
Gulp local: Local version 3.9.1
Ionic Framework Version: 1.3.3
Ionic CLI Version: 2.1.0
Ionic App Lib Version: 2.1.0-beta.1
ios-deploy version: 1.9.0
ios-sim version: 5.0.8
OS: Mac OS X El Capitan
Node Version: v6.8.1
Xcode version: Xcode 8.3.3 Build version 8E3004b
PS: in my package.json file, I see this:
"es6-promise-plugin": "file:node_modules/es6-promise-plugin",
How can I change this?

Answer 1

Oh dear Lord. I found the answer I was looking for, after I've struggled for hours. This link on Github is the answer to this problem.
Seems like npm version 5.x.x does not work with some ionic-plugins. I downgraded to npm 4 using npm install -g npm#4.6.1 and installing this plugin worked for me afterwards.
Ionic is so buggy sometimes. Very annoying.