Fixed: Adding series with unknown IMDB ID and series folder includes IMDB ID

src/NzbDrone.Core/Organizer/FileNameBuilder.cs

@@ -590,7 +590,7 @@ namespace NzbDrone.Core.Organizer
 
         private void AddIdTokens(Dictionary<string, Func<TokenMatch, string>> tokenHandlers, Series series)
         {
-            tokenHandlers["{ImdbId}"] = m => series.ImdbId;
+            tokenHandlers["{ImdbId}"] = m => series.ImdbId ?? string.Empty;
             tokenHandlers["{TvdbId}"] = m => series.TvdbId.ToString();
             tokenHandlers["{TvMazeId}"] = m => series.TvMazeId.ToString();
         }