Fix nullability errors in Jellyfin.Server.Implementations

Jellyfin.Server.Implementations/Users/DefaultPasswordResetProvider.cs

@@ -54,12 +54,17 @@ namespace Jellyfin.Server.Implementations.Users
             var usersReset = new List<string>();
             foreach (var resetFile in Directory.EnumerateFiles(_passwordResetFileBaseDir, $"{BaseResetFileName}*"))
             {
-                SerializablePasswordReset spr;
+                SerializablePasswordReset? spr;
                 await using (var str = File.OpenRead(resetFile))
                 {
                     spr = await JsonSerializer.DeserializeAsync<SerializablePasswordReset>(str).ConfigureAwait(false);
                 }
 
+                if (spr == null)
+                {
+                    throw new NullReferenceException(nameof(spr));
+                }
+
                 if (spr.ExpirationDate < DateTime.UtcNow)
                 {
                     File.Delete(resetFile);