Fix crash on codex operations with empty selection

Author: DSPaul

src/Models/CodexCollection.cs

@@ -585,6 +585,8 @@ public void DeleteCodex(Codex toDelete)
 
         public void DeleteCodices(IList<Codex> toDelete)
         {
+            if (!toDelete.Any()) return;
+
             Notification deleteWarnNotification = Notification.AreYouSureNotification;
             deleteWarnNotification.Body = $"You are about to remove {toDelete.Count} item{(toDelete.Count > 1 ? @"s" : @"")}. " +
                            $"This cannot be undone. " +
@@ -604,7 +606,8 @@ public void DeleteCodices(IList<Codex> toDelete)
 
         public void BanishCodices(IList<Codex> toBanish)
         {
-            if (toBanish is null) return;
+            if (!toBanish.SafeAny()) return;
+
             IEnumerable<string> toBanishPaths = toBanish.Select(codex => codex.Sources.Path);
             IEnumerable<string> toBanishURLs = toBanish.Select(codex => codex.Sources.SourceURL);
             IEnumerable<string> toBanishStrings = toBanishPaths

src/Models/CodexProperties/EnumerableProperty.cs

@@ -33,7 +33,7 @@ public override bool HasNewValue(IHasCodexMetadata toEvaluate, IHasCodexMetadata
                 return true;
             }
 
-            return !newVal!.SequenceEqual(refVal);
+            return !newVal.SequenceEqual(refVal);
         }
     }
 }

src/Services/CoverService.cs

@@ -87,6 +87,8 @@ public static async Task GetCover(Codex codex, ChooseMetaDataViewModel? chooseMe
 
         public static async Task GetCover(List<Codex> codices)
         {
+            if (!codices.Any()) return;
+
             var progressVM = ProgressViewModel.GetInstance();
             progressVM.ResetCounter();
             progressVM.TotalAmount = codices.Count;

src/Tools/ExtensionMethods.cs

@@ -2,6 +2,7 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
+using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
 using System.Linq;
 using System.Reflection;
@@ -172,7 +173,7 @@ public static IEnumerable<T> Flatten<T>(this IEnumerable<T> l, string method = "
             }
         }
 
-        public static bool SafeAny<T>(this IEnumerable<T>? l) => l is not null && l.Any();
+        public static bool SafeAny<T>([NotNullWhen(true)] this IEnumerable<T>? l) => l is not null && l.Any();
         #endregion
     }
 }

src/ViewModels/CodexViewModel.cs

@@ -108,7 +108,7 @@ public static bool CanOpenCodexOnline(Codex? toOpen)
         public RelayCommand<IList> OpenSelectedCodicesCommand => _openSelectedCodicesCommand ??= new(l => OpenSelectedCodices(l?.Cast<Codex>().ToList()));
         public static bool OpenSelectedCodices(IList<Codex>? toOpen)
         {
-            if (toOpen is null) return false;
+            if (!toOpen.SafeAny()) return false;
 
             if (toOpen.Count == 1)
             {
@@ -152,7 +152,7 @@ public static void EditCodex(Codex? toEdit)
         public static void EditCodices(IList? toEdit)
         {
             List<Codex>? toEditList = toEdit?.Cast<Codex>().ToList();
-            if (toEditList is null) return;
+            if (!toEditList.SafeAny()) return;
 
             if (toEditList.Count == 1)
             {
@@ -186,7 +186,8 @@ public static void FavoriteCodex(Codex? toFavorite)
         private static void FavoriteCodices(IList? toFavorite)
         {
             List<Codex>? toFavoriteList = toFavorite?.Cast<Codex>().ToList();
-            if (toFavoriteList is null) return;
+            if (!toFavoriteList.SafeAny()) return;
+
             if (toFavoriteList.Count == 1)
             {
                 FavoriteCodex(toFavoriteList.First());
@@ -247,6 +248,8 @@ public void MoveToCollection(object[]? par)
         /// <param name="toMoveList"></param>
         public static void MoveToCollection(CodexCollection targetCollection, List<Codex> toMoveList)
         {
+            if (!toMoveList.Any()) return;
+
             //Check if target Collection is valid
             if (targetCollection.DirectoryName == MainViewModel.CollectionVM.CurrentCollection.DirectoryName)
             {
@@ -324,6 +327,8 @@ public static void DeleteCodex(Codex? toDelete)
         public RelayCommand<IList> DeleteCodicesCommand => _deleteCodicesCommand ??= new(DeleteCodices);
         public static void DeleteCodices(IList? toDelete)
         {
+            if (toDelete == null || toDelete.Count == 0) return;
+
             MainViewModel.CollectionVM.CurrentCollection.DeleteCodices(toDelete?.Cast<Codex>().ToList() ?? new());
             MainViewModel.CollectionVM.FilterVM.ReFilter();
         }
@@ -341,6 +346,8 @@ public static void DeleteCodices(IList? toDelete)
         public RelayCommand<IList> BanishCodicesCommand => _banishCodicesCommand ??= new(BanishCodices);
         public static void BanishCodices(IList? toBanish)
         {
+            if (toBanish == null || toBanish.Count == 0) return;
+
             MainViewModel.CollectionVM.CurrentCollection.BanishCodices(toBanish?.Cast<Codex>().ToList() ?? new());
             DeleteCodices(toBanish);
         }
@@ -362,6 +369,8 @@ public static async Task StartGetMetaDataProcess(Codex? codex)
         }
         public static async Task StartGetMetaDataProcess(IList<Codex> codices)
         {
+            if (!codices.Any()) return;
+
             var progressVM = ProgressViewModel.GetInstance();
             progressVM.ResetCounter();
             progressVM.Text = "Getting MetaData";