* Use Guid.Equals(Guid) instead of the == override
* Ban the usage of Guid.Equals(Object) to prevent accidental boxing
* Compare to default(Guid) instead of Guid.Empty
AudioResolver.ResolveMultipleAudio method can attempt to access the first item in a List without checking if the list is empty which throws an ArgumentOutOfRangeException and stops the 'Scan Library' process.
```
Error Message:
System.ArgumentNullException : Value cannot be null. (Parameter 'source')
Stack Trace:
at System.Linq.ThrowHelper.ThrowArgumentNullException(ExceptionArgument argument)
at System.Linq.Enumerable.Select[TSource,TResult](IEnumerable`1 source, Func`2 selector)
at Emby.Server.Implementations.Library.LibraryManager.ResolveItem(ItemResolveArgs args, IItemResolver[] resolvers) in /home/vsts/work/1/s/Emby.Server.Implementations/Library/LibraryManager.cs:line 475
at Emby.Server.Implementations.Library.LibraryManager.ResolvePath(FileSystemMetadata fileInfo, IDirectoryService directoryService, IItemResolver[] resolvers, Folder parent, String collectionType, LibraryOptions libraryOptions) in /home/vsts/work/1/s/Emby.Server.Implementations/Library/LibraryManager.cs:line 618
at Emby.Server.Implementations.Library.LibraryManager.ResolvePath(FileSystemMetadata fileInfo, Folder parent) in /home/vsts/work/1/s/Emby.Server.Implementations/Library/LibraryManager.cs:line 536
at Emby.Server.Implementations.Library.LibraryManager.GetUserRootFolder() in /home/vsts/work/1/s/Emby.Server.Implementations/Library/LibraryManager.cs:line 812
at Emby.Server.Implementations.Library.LibraryManager.GetCollectionFolders(BaseItem item) in /home/vsts/work/1/s/Emby.Server.Implementations/Library/LibraryManager.cs:line 2080
at Emby.Server.Implementations.Library.LibraryManager.GetLibraryOptions(BaseItem item) in /home/vsts/work/1/s/Emby.Server.Implementations/Library/LibraryManager.cs:line 2116
at MediaBrowser.Providers.Manager.ProviderManager.SaveMetadata(BaseItem item, ItemUpdateType updateType, IEnumerable`1 savers) in /home/vsts/work/1/s/MediaBrowser.Providers/Manager/ProviderManager.cs:line 672
at MediaBrowser.Providers.Manager.ProviderManager.SaveMetadata(BaseItem item, ItemUpdateType updateType) in /home/vsts/work/1/s/MediaBrowser.Providers/Manager/ProviderManager.cs:line 655
at Emby.Server.Implementations.Library.LibraryManager.RunMetadataSavers(BaseItem item, ItemUpdateType updateReason) in /home/vsts/work/1/s/Emby.Server.Implementations/Library/LibraryManager.cs:line 2017
at Emby.Server.Implementations.Library.LibraryManager.UpdateItemsAsync(IReadOnlyList`1 items, BaseItem parent, ItemUpdateType updateReason, CancellationToken cancellationToken) in /home/vsts/work/1/s/Emby.Server.Implementations/Library/LibraryManager.cs:line 1975
at Emby.Server.Implementations.Library.LibraryManager.CreateRootFolder() in /home/vsts/work/1/s/Emby.Server.Implementations/Library/LibraryManager.cs:line 775
at Emby.Server.Implementations.Library.LibraryManager.get_RootFolder() in /home/vsts/work/1/s/Emby.Server.Implementations/Library/LibraryManager.cs:line 180
at Emby.Server.Implementations.IO.LibraryMonitor.Start() in /home/vsts/work/1/s/Emby.Server.Implementations/IO/LibraryMonitor.cs:line 135
at Emby.Server.Implementations.IO.LibraryMonitorStartup.RunAsync() in /home/vsts/work/1/s/Emby.Server.Implementations/IO/LibraryMonitorStartup.cs:line 26
at Emby.Server.Implementations.ApplicationHost.StartEntryPoints(IEnumerable`1 entryPoints, Boolean isBeforeStartup)+MoveNext() in /home/vsts/work/1/s/Emby.Server.Implementations/ApplicationHost.cs:line 518
at System.Threading.Tasks.Task.WhenAll(IEnumerable`1 tasks)
at Emby.Server.Implementations.ApplicationHost.RunStartupTasksAsync(CancellationToken cancellationToken) in /home/vsts/work/1/s/Emby.Server.Implementations/ApplicationHost.cs:line 502
at Jellyfin.Server.Integration.Tests.JellyfinApplicationFactory.CreateServer(IWebHostBuilder builder) in /home/vsts/work/1/s/tests/Jellyfin.Server.Integration.Tests/JellyfinApplicationFactory.cs:line 101
at Microsoft.AspNetCore.Mvc.Testing.WebApplicationFactory`1.EnsureServer()
at Microsoft.AspNetCore.Mvc.Testing.WebApplicationFactory`1.CreateDefaultClient(DelegatingHandler[] handlers)
at Microsoft.AspNetCore.Mvc.Testing.WebApplicationFactory`1.CreateDefaultClient(Uri baseAddress, DelegatingHandler[] handlers)
at Microsoft.AspNetCore.Mvc.Testing.WebApplicationFactory`1.CreateClient(WebApplicationFactoryClientOptions options)
at Microsoft.AspNetCore.Mvc.Testing.WebApplicationFactory`1.CreateClient()
at Jellyfin.Server.Integration.Tests.Controllers.ActivityLogControllerTests.ActivityLog_GetEntries_Ok() in /home/vsts/work/1/s/tests/Jellyfin.Server.Integration.Tests/Controllers/ActivityLogControllerTests.cs:line 21
--- End of stack trace from previous location ---
```
jakobkukla
Claus Vium
Bond_009
Stanislav Ionascu
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SenorSmartyPants
Joe Rogers
Dmitry Lyzo
cvium
Petrus.Z
Deathspike
Roel van Uden
Patrick Barron
Patrick Barron
Dixin
Fredrik Lindberg
Fernando Fernández
Jake King
BaronGreenback
Bill Thornton
artiume
Stephen Moore
Joshua M. Boniface
David