I use the plugin cordova-plugin-geolocation. My only issue is that the message prompt to allow location looks like this:
/var/container/bundle/applica
There are 3 possible reasons for displaying the path to the index.html instead of the name of your app:
As you say that you have installed the plugin and you are using it on device ready event, then it must be that you have forgotten to link the cordova.js in the index.html or the plugin wasn't installed correctly. Check that you have the cordova.js linked and if you have it, remove the plugin and add it again, removing and re adding the iOS platform might help too