return empty span instead of null for backwards compat

Emby.Naming/Video/CleanStringParser.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Diagnostics.CodeAnalysis;
 using System.Text.RegularExpressions;
 
 namespace Emby.Naming.Video
@@ -17,7 +16,7 @@ namespace Emby.Naming.Video
         /// <param name="expressions">List of regex to parse name and year from.</param>
         /// <param name="newName">Parsing result string.</param>
         /// <returns>True if parsing was successful.</returns>
-        public static bool TryClean(string name, IReadOnlyList<Regex> expressions, [NotNullWhen(true)] out ReadOnlySpan<char> newName)
+        public static bool TryClean(string name, IReadOnlyList<Regex> expressions, out ReadOnlySpan<char> newName)
         {
             var len = expressions.Count;
             for (int i = 0; i < len; i++)
@@ -32,11 +31,11 @@ namespace Emby.Naming.Video
             return false;
         }
 
-        private static bool TryClean(string name, Regex expression, [NotNullWhen(true)] out ReadOnlySpan<char> newName)
+        private static bool TryClean(string name, Regex expression, out ReadOnlySpan<char> newName)
         {
             if (string.IsNullOrEmpty(name))
             {
-                newName = null;
+                newName = ReadOnlySpan<char>.Empty;
                 return false;
             }
 
@@ -48,7 +47,7 @@ namespace Emby.Naming.Video
                 return true;
             }
 
-            newName = string.Empty;
+            newName = ReadOnlySpan<char>.Empty;
             return false;
         }
     }

Emby.Naming/Video/VideoResolver.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Linq;
 using Emby.Naming.Common;
@@ -147,7 +146,7 @@ namespace Emby.Naming.Video
         /// <param name="name">Raw name.</param>
         /// <param name="newName">Clean name.</param>
         /// <returns>True if cleaning of name was successful.</returns>
-        public bool TryCleanString(string name, [NotNullWhen(true)] out ReadOnlySpan<char> newName)
+        public bool TryCleanString(string name, out ReadOnlySpan<char> newName)
         {
             return CleanStringParser.TryClean(name, _options.CleanStringRegexes, out newName);
         }