unable to install plugin

[7seven7lst]

This error message happens when i try to install the plugin:
ionic plugin add https://github.com/Telerik-Verified-Plugins/Stripe --variable API_KEY=******

Installing "com.telerik.stripe" for ios
Saving plugin to package.json file
Error happened [TypeError: Object.keys called on non-object]
TypeError: Object.keys called on non-object
at Function.keys (native)
at Object.getPluginFromFetchJsonByLocator (/usr/local/lib/node_modules/ionic/node_modules/ionic-app-lib/lib/state.js:744:26)
at Object.savePlugin (/usr/local/lib/node_modules/ionic/node_modules/ionic-app-lib/lib/state.js:673:36)
at /usr/local/lib/node_modules/ionic/lib/ionic/cordova.js:95:22
at _fulfilled (/usr/local/lib/node_modules/ionic/node_modules/q/q.js:787:54)
at self.promiseDispatch.done (/usr/local/lib/node_modules/ionic/node_modules/q/q.js:816:30)
at Promise.promise.promiseDispatch (/usr/local/lib/node_modules/ionic/node_modules/q/q.js:749:13)
at /usr/local/lib/node_modules/ionic/node_modules/q/q.js:557:44
at flush (/usr/local/lib/node_modules/ionic/node_modules/q/q.js:108:17)
at process._tickCallback (node.js:355:11)