Fix nullability errors in MediaBrowser.LocalMetadata

MediaBrowser.LocalMetadata/Images/LocalImageProvider.cs

@@ -486,7 +486,7 @@ namespace MediaBrowser.LocalMetadata.Images
             return false;
         }
 
-        private FileSystemMetadata GetImage(IEnumerable<FileSystemMetadata> files, string name)
+        private FileSystemMetadata? GetImage(IEnumerable<FileSystemMetadata> files, string name)
         {
             return files.FirstOrDefault(i => !i.IsDirectory && string.Equals(name, _fileSystem.GetFileNameWithoutExtension(i), StringComparison.OrdinalIgnoreCase) && i.Length > 0);
         }

MediaBrowser.LocalMetadata/Parsers/BaseItemXmlParser.cs

@@ -683,7 +683,7 @@ namespace MediaBrowser.LocalMetadata.Parsers
                 default:
                 {
                     string readerName = reader.Name;
-                    if (_validProviderIds!.TryGetValue(readerName, out string providerIdValue))
+                    if (_validProviderIds!.TryGetValue(readerName, out string? providerIdValue))
                     {
                         var id = reader.ReadElementContentAsString();
                         if (!string.IsNullOrWhiteSpace(id))

MediaBrowser.LocalMetadata/Savers/BaseXmlSaver.cs

@@ -127,7 +127,13 @@ namespace MediaBrowser.LocalMetadata.Savers
 
         private void SaveToFile(Stream stream, string path)
         {
-            Directory.CreateDirectory(Path.GetDirectoryName(path));
+            var directory = Path.GetDirectoryName(path);
+            if (directory == null)
+            {
+                throw new NullReferenceException(nameof(directory));
+            }
+
+            Directory.CreateDirectory(directory);
             // On Windows, savint the file will fail if the file is hidden or readonly
             FileSystem.SetAttributes(path, false, false);