Fixed: Deleted books removed from UI

src/NzbDrone.Core/AuthorStats/AuthorStatisticsService.cs

@@ -114,7 +114,12 @@ namespace NzbDrone.Core.AuthorStats
         public void Handle(BookFileDeletedEvent message)
         {
             _cache.Remove("AllAuthors");
-            _cache.Remove(message.BookFile.Author.Value.Id.ToString());
+
+            var authorId = message.BookFile.Author?.Value?.Id.ToString();
+            if (authorId != null)
+            {
+                _cache.Remove(authorId);
+            }
         }
     }
 }

src/Readarr.Api.V1/Books/BookController.cs

@@ -28,6 +28,7 @@ namespace Readarr.Api.V1.Books
         IHandle<BookGrabbedEvent>,
         IHandle<BookEditedEvent>,
         IHandle<BookUpdatedEvent>,
+        IHandle<BookDeletedEvent>,
         IHandle<BookImportedEvent>,
         IHandle<TrackImportedEvent>,
         IHandle<BookFileDeletedEvent>

src/Readarr.Api.V1/Books/BookResource.cs

@@ -52,7 +52,7 @@ namespace Readarr.Api.V1.Books
             var selectedEdition = model.Editions?.Value.Where(x => x.Monitored).SingleOrDefault();
 
             var title = selectedEdition?.Title ?? model.Title;
-            var authorTitle = $"{model.Author.Value.Metadata.Value.SortNameLastFirst} {title}";
+            var authorTitle = $"{model.Author?.Value?.Metadata?.Value?.SortNameLastFirst} {title}";
 
             return new BookResource
             {