[Xamarin.Mac] RadioButton : InvalidCastException on click

[Suryask0]

Description

In the XF 5.0 pre release 4, clicking on the radio button would throw an InvalidCastException,

System.InvalidCastException: Specified cast is not valid.
at Xamarin.Forms.Platform.MacOS.RadioButtonRenderer.OnButtonActivated (System.Object sender, System.EventArgs eventArgs) [0x00006] in <8a8d612caf0944fe942d18a9ec2fe3d3>:0
at AppKit.ActionDispatcher.OnActivated (Foundation.NSObject sender) [0x00010] in /Library/Frameworks/Xamarin.Mac.framework/Versions/6.18.2.1/src/Xamarin.Mac/AppKit/ActionDispatcher.cs:50
at at (wrapper managed-to-native) ObjCRuntime.Messaging.void_objc_msgSendSuper_IntPtr(intptr,intptr,intptr)
at AppKit.NSControl.MouseDown (AppKit.NSEvent theEvent) [0x00040] in /Library/Frameworks/Xamarin.Mac.framework/Versions/6.18.2.1/src/Xamarin.Mac/NSControl.g.cs:465
at Xamarin.Forms.Platform.MacOS.RadioButtonRenderer+FormsNSButton.MouseDown (AppKit.NSEvent theEvent) [0x00011] in <8a8d612caf0944fe942d18a9ec2fe3d3>:0
at at (wrapper managed-to-native) AppKit.NSApplication.NSApplicationMain(int,string[])
at AppKit.NSApplication.Main (System.String[] args) [0x00040] in /Library/Frameworks/Xamarin.Mac.framework/Versions/6.18.2.1/src/Xamarin.Mac/AppKit/NSApplication.cs:109
at TestRadio.Mac.MainClass.Main (System.String[] args) [0x00017] in /Users/../Projects/TestRadioButton/TestRadio.Mac/Main.cs:11

Steps to Reproduce

1. Launch the attached repo on Mac platform,
2. click on the radio button.

Expected Behavior

• Radio button needs to be checked/selected

Actual Behavior

• Throws InvalidCastException

Basic Information

• Version with issue: XF 5.0 pre 4, XF 5.0 pre 1
• IDE:
• Platform Target Frameworks:
  • Xamarin.Mac Modern
• Nuget Packages: Xamarin.Forms 5.0.0.1709 -pre4

Reproduction Link

TestRadioButton.zip