Fix crasher, add logging, don't ignore exceptions

Author: shana

src/GitHub.App/ViewModels/PullRequestCreationViewModel.cs

@@ -17,6 +17,7 @@
 using System.Reactive;
 using System.Diagnostics.CodeAnalysis;
 using Octokit;
+using NLog;
 
 namespace GitHub.ViewModels
 {
@@ -25,6 +26,8 @@ namespace GitHub.ViewModels
     [SuppressMessage("Microsoft.Design", "CA1001:TypesThatOwnDisposableFieldsShouldBeDisposable")]
     public class PullRequestCreationViewModel : BaseViewModel, IPullRequestCreationViewModel
     {
+        static readonly Logger log = LogManager.GetCurrentClassLogger();
+
         readonly IRepositoryHost repositoryHost;
         readonly ISimpleRepositoryModel activeRepo;
         readonly Subject<Unit> initializationComplete = new Subject<Unit>();
@@ -36,7 +39,7 @@ public class PullRequestCreationViewModel : BaseViewModel, IPullRequestCreationV
              IPullRequestService service, INotificationService notifications)
              : this(connectionRepositoryHostMap.CurrentRepositoryHost, teservice.ActiveRepo, service, notifications)
          {}
-        
+
         public PullRequestCreationViewModel(IRepositoryHost repositoryHost, ISimpleRepositoryModel activeRepo,
             IPullRequestService service, INotificationService notifications)
         {
@@ -78,18 +81,18 @@ public PullRequestCreationViewModel(IRepositoryHost repositoryHost, ISimpleRepos
                 .Subscribe(x => notifications.ShowError(BranchValidator.ValidationResult.Message));
 
             createPullRequest = ReactiveCommand.CreateAsyncObservable(whenAnyValidationResultChanges,
-                _ => service.CreatePullRequest(repositoryHost, activeRepo, PRTitle, Description, SourceBranch, TargetBranch)
-            );
-            createPullRequest.ThrownExceptions.Subscribe(ex =>
-            {
-                if (!ex.IsCriticalException())
-                {
-                    //TODO:Will need a uniform solution to HTTP exception message handling
-                    var apiException = ex as ApiValidationException;
-                    var error = apiException?.ApiError?.Errors?.FirstOrDefault();
-                    notifications.ShowError(error?.Message ?? ex.Message);
-                }
-            });
+                _ => service
+                    .CreatePullRequest(repositoryHost, activeRepo, PRTitle, Description ?? String.Empty, SourceBranch, TargetBranch)
+                    .Catch<IPullRequestModel, Exception>(ex =>
+                    {
+                        log.Error(ex);
+
+                        //TODO:Will need a uniform solution to HTTP exception message handling
+                        var apiException = ex as ApiValidationException;
+                        var error = apiException?.ApiError?.Errors?.FirstOrDefault();
+                        notifications.ShowError(error?.Message ?? ex.Message);
+                        return Observable.Empty<IPullRequestModel>();
+                    }));
         }
 
         public override void Initialize([AllowNull] ViewWithData data)