Application xamarin.forms stopped from nowhere

I was making a code to receive notification and suddenly the application does not run anymore. Compiles, Deploys, but it takes time to consume the service and this message appears: Android project stopped continue / ok. My MainActivity:

using System;

using Android.App;
using Android.Content.PM;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Android.OS;

using Android.Gms.Common;
using Firebase.Messaging;
using Firebase.Iid;
using Android.Util;
using PushNotification.Plugin;
using Newtonsoft.Json.Linq;
using PushNotification.Plugin.Abstractions;
using Android.Content;
using Java.Lang;

namespace Autorizador.Droid
{
    [Activity(Label = "Autorizador", Icon = "@drawable/icon", Theme = "@style/MainTheme", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation)]
    public class MainActivity : //global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
         global::Xamarin.Forms.Platform.Android.FormsApplicationActivity
    {
        public static Context AppContext;
        protected override void OnCreate(Bundle bundle)
        {
            //TabLayoutResource = Resource.Layout.Tabbar;
            //ToolbarResource = Resource.Layout.Toolbar;

            base.OnCreate(bundle);

            global::Xamarin.Forms.Forms.Init(this, bundle);

            //AppContext = this.ApplicationContext;

            //CrossPushNotification.Initialize<CrossPushNotificationListener>("840100012845");

            //StartPushService();

            LoadApplication(new App());            
        }

        public static void StartPushService()
        {
            AppContext.StartService(new Intent(AppContext, typeof(PushNotificationService)));

            if (Android.OS.Build.VERSION.SdkInt >= Android.OS.BuildVersionCodes.Kitkat)
            {

                PendingIntent pintent = PendingIntent.GetService(AppContext, 0, new Intent(AppContext, typeof(PushNotificationService)), 0);
                AlarmManager alarm = (AlarmManager)AppContext.GetSystemService(Context.AlarmService);
                alarm.Cancel(pintent);
            }
        }

        public static void StopPushService()
        {
            AppContext.StopService(new Intent(AppContext, typeof(PushNotificationService)));
            if (Android.OS.Build.VERSION.SdkInt >= Android.OS.BuildVersionCodes.Kitkat)
            {
                PendingIntent pintent = PendingIntent.GetService(AppContext, 0, new Intent(AppContext, typeof(PushNotificationService)), 0);
                AlarmManager alarm = (AlarmManager)AppContext.GetSystemService(Context.AlarmService);
                alarm.Cancel(pintent);
            }
        }
    }
}

and my App.xaml.cs

using PushNotification.Plugin;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using Xamarin.Forms;
using System.Threading.Tasks;
using System.Threading;
using System.Diagnostics;

namespace Autorizador
{
    public partial class App : Application
    {
        public static CancellationTokenSource CancellationToken { get; set; }
        private Label _label = new Label();
        public App()
        {
            InitializeComponent();

            //MainPage = new Autorizador.MainPage();
            MainPage = new NavigationPage(new Autorizador.MainPage());
        }


        protected override void OnStart()
        {
            //CrossPushNotification.Current.Unregister();
            //CrossPushNotification.Current.Register();
        }

        protected override void OnSleep()
        {
            // Handle when your app sleeps
        }

        protected override void OnResume()
        {
            // Handle when your app resumes
        }
    }
}

I put the using, because it could be that something should not be. What I did and did this all week, comment and uncomment what's on MainActivity in an attempt to get notifications.

EDIT1

I put a break at several points, but when it arrives at InitializeComponent () , the system stops. I give F10 and nothing, the cursor stays in the same place. Below the MainPage class:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Xamarin.Forms;
using Autorizador.Model;
using Autorizador.Service;

namespace Autorizador
{
    public partial class MainPage : ContentPage
    {
        DataService dataService;
        List<Liberacao> lib;
        int _idorcamento = 0;
        public MainPage()
        {
            InitializeComponent();
            dataService = new DataService();
            AtualizaDados();
            //Content = new ScrollView { Content = listaLibera, Orientation = ScrollOrientation.Both };
        }

        protected override void OnAppearing()
        {
            base.OnAppearing();

            LimpaGeral();

            AtualizaDados();
        }

        private async void AtualizaDados()
        {
            lib = await dataService.GetLiberaAsync();
            listaLibera.ItemsSource = lib.OrderBy(item => item.Cliente).ToList();
        }

        private void listaLibera_ItemSelected(object sender, SelectedItemChangedEventArgs e)
        {
            try
            {
                var libera = e.SelectedItem as Liberacao;

                _idorcamento = libera.IdOrcamento;

                lblTipoVenda.Text = "Tipo de Venda: " + libera.TipoVenda;
                lblVencimento.Text = "Vencimento: " + libera.Vencimento;
                lblJuros.Text = "Juros: " + libera.Juros.ToString();
                lblEntrada.Text = "Entrada: " + libera.Entrada;
                lblAcrescimo.Text = "Acréscimo: " + libera.Acrescimo;
                lblDesconto.Text = "Desconto: " + libera.Desconto;
                btnItens.IsEnabled = true;
            }
            catch(Exception ex)
            {
                btnItens.IsEnabled = false;
                throw new Exception(ex.Message);
            }
        }

        private async void btnItens_Clicked(object sender, EventArgs e)
        {
            await Navigation.PushModalAsync(new MainPageItens(_idorcamento, lib));
        }
        private void LimpaGeral()
        {
            lblTipoVenda.Text = "Tipo de Venda:";
            lblVencimento.Text = "Vencimento:";
            lblJuros.Text = "Juros:";
            lblEntrada.Text = "Entrada:";
            lblAcrescimo.Text = "Acréscimo:";
            lblDesconto.Text = "Desconto:";
            btnItens.IsEnabled = false;
        }
    }
}