Fix bad origin pkm base egg moves

returns null, then was called ToList => exception
changes return value to same type as other returns

PKHeX/Legality/Core.cs

@@ -1045,7 +1045,7 @@ internal static IEnumerable<int> getBaseEggMoves(PKM pkm, int skipOption, GameVe
                         return LevelUpSM[index].getMoves(lvl);
                     break;
             }
-            return null;
+            return new int[0];
         }
         internal static List<int>[] getExclusiveEvolutionMoves(PKM pkm, int Species,DexLevel[][] evoChains, GameVersion Version)
         {