MobileAccessibility doesn't recognize installed Cordova plugin

[janpio]

I'm submitting a ...
[x] bug report
[ ] feature request

Current behavior:
Even if you install the MobileAccessibility by the docs it doesn't work on devices. It just doesn't recognize the installed (and working if used directly) Cordova plugin. You always get:

My guess: The pluginRef with MobileAccessibility is wrong and should be window.MobileAccessibility.

(I tried to fix this directly in the .js of the installed @ionic-native plugin, but that didn't work - so I am not sure and couldn't test this.)

Expected behavior:
Plugin works.

Steps to reproduce:
A project with both Ionic Native and direct access to the Cordova plugin is here: https://github.com/janpio/ionic-native-mobile-accessibility

Related code:

doesn't work:

     this.mobileAccessibility.getTextZoomCallback().then(res => {
        console.log('his.mobileAccessibility.getTextZoomCallback ', JSON.stringify(res));
      });

does work:

      function getTextZoomCallback(textZoom) {
        console.log('Current text zoom = ' + textZoom + '%')
      }
      window.MobileAccessibility.getTextZoom(getTextZoomCallback);

[KiwiKilian]

Can confirm this problem. When using window.MobileAcessiblity it does give me correct results in iOS Simulator, but also throwing an error Property 'MobileAccessibility' does not exist on type 'Window'..