Fix exception caused by #1096
```cs
MediaBrowser.Common.Extensions.ResourceNotFoundException: Configuration
with key subtitles not found.
at
Emby.Server.Implementations.AppBase.BaseConfigurationManager.<>c__DisplayClass42_0.<GetConfiguration>b__0(String
k) in
/home/pi/dev/jellyfin/Emby.Server.Implementations/AppBase/BaseConfigurationManager.cs:line
247
at
System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey
key, Func`2 valueFactory)
at
Emby.Server.Implementations.AppBase.BaseConfigurationManager.GetConfiguration(String
key) in
/home/pi/dev/jellyfin/Emby.Server.Implementations/AppBase/BaseConfigurationManager.cs:line
238
at
MediaBrowser.Providers.MediaInfo.FFProbeVideoInfo.AddExternalSubtitles(Video
video, List`1 currentStreams, MetadataRefreshOptions
options, CancellationToken cancellationToken) in
/home/pi/dev/jellyfin/MediaBrowser.Providers/MediaInfo/FFProbeVideoInfo.cs:line
486
at
MediaBrowser.Providers.MediaInfo.FFProbeVideoInfo.Fetch(Video
video, CancellationToken cancellationToken, MediaInfo
mediaInfo, BlurayDiscInfo blurayInfo,
MetadataRefreshOptions options) in
/home/pi/dev/jellyfin/MediaBrowser.Providers/MediaInfo/FFProbeVideoInfo.cs:line
204
at
MediaBrowser.Providers.MediaInfo.FFProbeVideoInfo.ProbeVideo[T](T
item, MetadataRefreshOptions options,
CancellationToken cancellationToken) in
/home/pi/dev/jellyfin/MediaBrowser.Providers/MediaInfo/FFProbeVideoInfo.cs:line
119
at
MediaBrowser.Providers.Manager.MetadataService`2.RunCustomProvider(ICustomMetadataProvider`1
provider, TItemType item, String logName,
MetadataRefreshOptions options, RefreshResult
refreshResult, CancellationToken cancellationToken)
in
/home/pi/dev/jellyfin/MediaBrowser.Providers/Manager/MetadataService.cs:line
806
```
764c901cd7