[Mono.Android] Fix UnhandledExceptionRaiser not firing in .NET 10

[jonathanpeppers]

Context: dotnet/java-interop#1275
Fixes: https://devdiv.visualstudio.com/DevDiv/_workitems/edit/2842209

dotnet/java-interop#1275 eliminated JNINativeWrapper.CreateDelegate() from generated binding marshal methods. The old code path routed exceptions through AndroidEnvironment.UnhandledException(), which fires the UnhandledExceptionRaiser event. The new code path calls JniRuntime.OnUserUnhandledException(), which only calls SetPendingException() and never invokes AndroidEnvironment.UnhandledException().

Fix by overriding OnUserUnhandledException() in AndroidRuntime to call AndroidEnvironment.TryRaiseUnhandledException() before delegating to the base implementation. If a subscriber sets Handled = true, the exception is swallowed and not transitioned to JNI.

Refactor AndroidEnvironment.UnhandledException() to extract the event- raising logic into TryRaiseUnhandledException() so it can be called from both the old and new code paths.

Tests

Add a test that verifies both UnhandledExceptionRaiser and AppDomain.UnhandledException fire when an unhandled exception is thrown from a button click handler.

The test:

1. Registers both UnhandledExceptionRaiser (with e.Handled = true) and AppDomain.UnhandledException handlers
2. Throws from the button click delegate
3. Asserts UnhandledExceptionRaiser fires via logcat

[Copilot]

Pull request overview

Fixes a regression where managed exceptions thrown from generated binding marshal methods no longer trigger AndroidEnvironment.UnhandledExceptionRaiser on .NET 10+ (after the switch away from JNINativeWrapper.CreateDelegate()), by routing the new JniRuntime.OnUserUnhandledException() path through the same event-raising mechanism.

Changes:

• Override AndroidRuntime.OnUserUnhandledException() to invoke AndroidEnvironment.TryRaiseUnhandledException() and swallow the exception when Handled=true.
• Refactor AndroidEnvironment.UnhandledException() to extract reusable event-raising logic into TryRaiseUnhandledException().
• Add a device integration test that throws from a button click handler and validates logcat output for UnhandledExceptionRaiser.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
tests/MSBuildDeviceIntegration/Tests/InstallAndRunTests.cs	Adds a device test that throws from a UI click handler and checks logcat for the raised unhandled-exception event.
src/Mono.Android/Android.Runtime/AndroidRuntime.cs	Overrides OnUserUnhandledException() to raise UnhandledExceptionRaiser for the new Java.Interop exception path.
src/Mono.Android/Android.Runtime/AndroidEnvironment.cs	Extracts event-raising into TryRaiseUnhandledException() so both legacy and new paths can share it.