Updating the CanExecute command property for a disposed MaterialButton causes a crash

[michaelkollmann]

Describe the bug
When updating the CanExecute property for an already disposed MaterialButton a crash occours.
This issue does not exist when using the regular Xamarin.Forms Button.

To Reproduce
Steps to reproduce the behavior:

1. My application opens a modal dialog page
2. In this dialog I click a "Save" button which closes the dialog
3. To prevent clicking the button twice the command sets the CanExecute property to false while the command is being executed
4. Now the dialog has been closed and is starting to be disposed. The command completes and the CanExecute property changes back from false to true.
5. Now the application crashes with the following error:

System.ObjectDisposedException: Cannot access a disposed object. Object name: 'Android.Support.V7.Widget.AppCompatButton'.

I'm using the latest XF.Material library, version 1.3.0.2. All my Xamarin.Android.* libraries are version 28.0.0

Expected behavior
The application does not crash.

Screenshots
If applicable, add screenshots to help explain your problem.

Environment:

• Device: Xiaomi Red mi 2
• OS: Android 8.1

[contrix09]

Will look into this.

[contrix09]

I can't seem to replicate this. What do you use to show the modal page?

[yankarinRG]

Still persists as of 1.6.4