check palette references

OpenRA.Mods.Common/Traits/World/PaletteFromFile.cs

@@ -17,16 +17,20 @@ namespace OpenRA.Mods.Common.Traits
 {
 	class PaletteFromFileInfo : ITraitInfo
 	{
-		[FieldLoader.Require]
+		[FieldLoader.Require, PaletteDefinition]
 		[Desc("internal palette name")]
 		public readonly string Name = null;
+
 		[Desc("If defined, load the palette only for this tileset.")]
 		public readonly string Tileset = null;
+
 		[FieldLoader.Require]
 		[Desc("filename to load")]
 		public readonly string Filename = null;
+
 		[Desc("Map listed indices to shadow. Ignores previous color.")]
 		public readonly int[] ShadowIndex = { };
+
 		public readonly bool AllowModifiers = true;
 
 		public object Create(ActorInitializer init) { return new PaletteFromFile(init.World, this); }