Fix defaultmod.

OpenRA.Game/Graphics/SequenceProvider.cs

@@ -24,7 +24,9 @@ namespace OpenRA.Graphics
 		public static void Initialize(string[] sequenceFiles)
 		{
 			units = new Dictionary<string, Dictionary<string, Sequence>>();
-			
+			if (sequenceFiles.Length == 0)
+				return;
+
 			var sequences = sequenceFiles
 				.Select(s => MiniYaml.FromFile(s))
 				.Aggregate(MiniYaml.Merge);