Defining a platform-specific behavior in XAML for iOS throws a NullReferenceException on android/release

[DanTravison]

My goal is to add a Behavior to a layout control only on iOS in Xaml using the below syntax.

<controls:Toolbar.Behaviors>
    <OnPlatform x:TypeArguments="Behavior">
        <On Platform="iOS">
            <ios:MyBehavior/>
        </On>
    </OnPlatform>
</controls:Toolbar.Behaviors>

My expectation is the Xaml should be a NOP on other platforms but, instead, I see a NullReferenceException on android when building for release:

[MonoDroid] android.runtime.JavaProxyThrowable: [System.NullReferenceException]: Object reference not set to an instance of an object

[MonoDroid] 	at Microsoft.Maui.Controls.AttachedCollection`1[[Microsoft.Maui.Controls.Behavior, Microsoft.Maui.Controls, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].InsertItem + 0x1d(Unknown Source)

[MonoDroid] 	at System.Collections.ObjectModel.Collection`1[[Microsoft.Maui.Controls.Behavior, Microsoft.Maui.Controls, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].Add + 0x1f(Unknown Source)

[MonoDroid] 	at WordInsights.Views.MainPage.InitializeComponent + 0x3d1(Unknown Source)

From the failure, it appears I need a stub Behavior for all other platforms.

• Is this right solution or is it an issue with AttachedCollection?
  • It seems counter-intuitive to create, essentially, dead code.
• If so, can I safely override OnAttached and OnDetached and do nothing or will that cause other problems?

FWIW: Querying CoPilot suggests the same Xaml I'm using above.

I'm using Maui 9.0.120.