Xamarin表单 - 随机错误 - android.runtime.JavaProxyThrowable：System.ArgumentOutOfRangeException

Question

在上个月我们在使用Xamarin Forms开发的Android应用程序中遇到问题。该应用程序通常适用于Android 4.4或更低版本的设备，在大量使用后它开始显示以下错误

    java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:761)
    at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.reflect.InvocationTargetException
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:511)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:994)
    ... 2 more
Caused by: android.runtime.JavaProxyThrowable: System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index
  at System.ThrowHelper.ThrowArgumentOutOfRangeException (System.ExceptionArgument argument, System.ExceptionResource resource) [0x00011] in <af6732aa09ee4b909854dccb0d522f24>:0 
  at System.ThrowHelper.ThrowArgumentOutOfRangeException () [0x00000] in <af6732aa09ee4b909854dccb0d522f24>:0 
  at System.Collections.Generic.List`1[T].get_Item (System.Int32 index) [0x0000c] in <af6732aa09ee4b909854dccb0d522f24>:0 
  at Xamarin.Forms.NavigationProxy.PopModal () [0x00012] in <b0fc14d4e5b04749b7241d1235a68329>:0 
  at Xamarin.Forms.NavigationProxy.OnPopModal (System.Boolean animated) [0x00012] in <b0fc14d4e5b04749b7241d1235a68329>:0 
  at Xamarin.Forms.NavigationProxy.PopModalAsync () [0x00000] in <b0fc14d4e5b04749b7241d1235a68329>:0 
  at AppTailler.SelecionarMotivos+<SalvarClicked>d__13.MoveNext () [0x0036b] in <014096e14bed4164874e3d1600ae8a7c>:0 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000c] in <af6732aa09ee4b909854dccb0d522f24>:0 
  at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<ThrowAsync>m__0 (System.Object state) [0x00000] in <af6732aa09ee4b909854dccb0d522f24>:0 
  at Android.App.SyncContext+<Post>c__AnonStorey0.<>m__0 () [0x00000] in <a5074c74656e4a848b5b501002439cbc>:0 
  at Java.Lang.Thread+RunnableImplementor.Run () [0x0000b] in <a5074c74656e4a848b5b501002439cbc>:0 
  at Java.Lang.IRunnableInvoker.n_Run (System.IntPtr jnienv, System.IntPtr native__this) [0x00009] in <a5074c74656e4a848b5b501002439cbc>:0 
  at (wrapper dynamic-method) System.Object:5567cc09-fb12-48c3-9293-77a23494730a (intptr,intptr)
    at mono.java.lang.RunnableImplementor.n_run(Native Method)
    at mono.java.lang.RunnableImplementor.run(RunnableImplementor.java:30)
    at android.os.Handler.handleCallback(Handler.java:615)
    at android.os.Handler.dispatchMessage(Handler.java:92)
    at android.os.Looper.loop(Looper.java:137)
    at android.app.ActivityThread.main(ActivityThread.java:4895)
    ... 5 more

在这些版本中重新安装应用程序时，它会恢复正常操作，一段时间后再次导致同样的错误。

以下是发生错误的代码行。

public async void SalvarClicked(object sender, EventArgs e)
    {
        if (motivoSelecionado == null
            && String.IsNullOrEmpty(escreverMotivo.Text)
            && (motivosSelecionados.Any() || motivosSelecionados == null || motivosSelecionados.Count == 0))
        {
            await DisplayAlert("Alerta", "Você deve inserir pelo menos um motivo.", "Sim");
            return;
        }
        else
        {
            using (var dados = new DataAccess())
            {
                if (!String.IsNullOrEmpty(escreverMotivo.Text))
                {
                    var motivoNovo = await DisplayAlert("Alerta", "Você está inserindo um motivo novo deseja continuar?", "Sim", "Não");
                    if (!motivoNovo)
                    {
                        return;
                    }
                    else
                    {
                        if (motivoSelecionado == null)
                        {
                            motivos mot = new motivos()
                            {
                                IdTextoVistoria = 0,
                                idSubItem = 0,
                                txtNumTexto = 0,
                                txtTexto = escreverMotivo.Text
                            };
                            motivoSelecionado = mot;
                        }
                        motivoSelecionado.IdTextoVistoria = 0;
                        motivoSelecionado.txtTexto = escreverMotivo.Text;
                    }
                }
                auditoria auditoria = dados.GetAuditoria(idAudit);
                auditoria.IdAuditoria = auditoria.IdAuditoria;
                if (motivoSelecionado != null)
                {
                    auditoria.SubDescId = motivoSelecionado.IdTextoVistoria;
                    auditoria.SubDescTexto = motivoSelecionado.txtTexto;
                }
                auditoria.SubPhotoUrl = auditoria.SubPhotoUrl;
                auditoria.SubMotivoBytes = auditoria.SubMotivoBytes;
                if (_mediaFile != null)
                {
                    var stream = _mediaFile.GetStream();
                    targetImageByte = ReadFully(stream);
                    auditoria.SubMotivoBytes = targetImageByte;
                }
                dados.AtualizarAuditoria(auditoria);
                await DisplayAlert("Sucesso", "Salvo com sucesso!", "Ok");
            }
        }
        await App.NP.Navigation.PopModalAsync();
    }

我不知道代码中是否存在问题，或者android版本是否影响它。

无论如何，欢迎任何帮助