fix loading seasons with empty episode plot (#67)

ErsatzTV.Application/MediaCards/Mapper.cs

@@ -18,7 +18,7 @@ namespace ErsatzTV.Application.MediaCards
 
         internal static TelevisionSeasonCardViewModel ProjectToViewModel(Season season) =>
             new(
-                season.Show.ShowMetadata.HeadOrNone().Map(m => m.Title).IfNone(string.Empty),
+                season.Show.ShowMetadata.HeadOrNone().Match(m => m.Title ?? string.Empty, () => string.Empty),
                 season.Id,
                 season.SeasonNumber,
                 GetSeasonName(season.SeasonNumber),
@@ -32,12 +32,16 @@ namespace ErsatzTV.Application.MediaCards
             new(
                 episodeMetadata.EpisodeId,
                 episodeMetadata.ReleaseDate ?? DateTime.MinValue,
-                episodeMetadata.Episode.Season.Show.ShowMetadata.HeadOrNone().Map(m => m.Title).IfNone(string.Empty),
+                episodeMetadata.Episode.Season.Show.ShowMetadata.HeadOrNone().Match(
+                    m => m.Title ?? string.Empty,
+                    () => string.Empty),
                 episodeMetadata.Episode.Season.ShowId,
                 episodeMetadata.Episode.SeasonId,
                 episodeMetadata.Episode.EpisodeNumber,
                 episodeMetadata.Title,
-                episodeMetadata.Episode.EpisodeMetadata.HeadOrNone().Map(em => em.Plot).IfNone(string.Empty),
+                episodeMetadata.Episode.EpisodeMetadata.HeadOrNone().Match(
+                    em => em.Plot ?? string.Empty,
+                    () => string.Empty),
                 GetThumbnail(episodeMetadata));
 
         internal static MovieCardViewModel ProjectToViewModel(MovieMetadata movieMetadata) =>