Reproduction of Frame issue

While playing around with UWP, Xamarin Forms and Caliburn Micro I came across a weird and hard to debug exception.

I traced it down to the following:

• xamarin Forms UWP
• CommandBar with a single AppBarButton without an icon set (this is coming from the master-detail template in VS2017)
• Set the Window.Current.Content to a Page instead of a Frame (coming from the setup guide of Caliburn Micro for xamarin forms with UWP)

The exception can be solved in 2 ways:

• Set a valid icon for the AppBarButton
• Set the rootelement to a Frame

App1

• A stripped Xamarin Forms master-detail template app, with only a UWP project and the PCL
• When the App starts, a popup will show what to use as rootelement - a Frame or a Page
• With the Frame, it runs as expected
• With the Page, it hits an exception (without stacktrace!!)

App2

• A blank UWP app without Xamarin Forms
• Rootelement set to Page
• CommandBar with iconless AppBarButton

Runs without exceptions