Forms blows up Insight?

I have a really simple page:

    public AccountsPage()
    {

        toolbarItem = new ToolbarItem("?", "accounts.png",async  () =>
        {
            await DisplayAlert("Hi", "Clicked me",null);
        }, 0, 0);

When I add the **DisplayAlert **and tap the toolbar button on a real iPhone 5s running 8.1, Insight explodes:

????

Exception in OnUnhandledException:

Mono.Debugger.Soft.AbsentInformationException: Debug information is not
available for this frame.

at Mono.Debugger.Soft.VirtualMachine.ErrorHandler(Object sender,
ErrorHandlerEventArgs args)

at Mono.Debugger.Soft.Connection.SendReceive(CommandSet command_set, Int32
command, PacketWriter packet)

at Mono.Debugger.Soft.Connection.StackFrame_GetThis(Int64 thread_id, Int64id)

at Mono.Debugger.Soft.StackFrame.GetThis()

at Mono.Debugging.Soft.ThisValueReference.get_Value()

atMono.Debugging.Soft.SoftDebuggerAdaptor.GetHoistedLocalVariables(SoftEvaluationContextcx, ValueReference vthis)

at
Mono.Debugging.Soft.SoftDebuggerAdaptor.OnGetLocalVariables(EvaluationContextctx)

atMono.Debugging.Evaluation.ExpressionEvaluator.GetLocalVariables(EvaluationContextctx)

at Mono.Debugging.Evaluation.BaseBacktrace.GetFrameInfo(Int32 frameIndex,EvaluationOptions options, Boolean ignoreEvalStatus)

at Mono.Debugging.Evaluation.BaseBacktrace.GetException(Int32 frameIndex,EvaluationOptions options)

at
Xamarin.VisualStudio.Debugger.MonoToolsDebuggerSession.OnUnhandledException(Objectsender, TargetEventArgs args)