another fix for mergeables

Source/PerformanceFish/JobSystem/WorkGiver_MergeOptimization.cs

@@ -3,6 +3,8 @@
 // License, v. 2.0. If a copy of the MPL was not distributed with this
 // file, You can obtain one at https://mozilla.org/MPL/2.0/.
 
+using Verse.AI;
+
 namespace PerformanceFish.JobSystem;
 
 public class WorkGiver_MergeOptimization : ClassWithFishPatches
@@ -12,10 +14,15 @@ public class WorkGiver_MergeOptimization : ClassWithFishPatches
 		public override string Description => "Removes mergeables from ListerMergeables if they no longer qualify as mergeable when trying to check for a merging job on them. Vanilla RimWorld just fails and keeps them in";
 		public override MethodBase TargetMethodInfo => AccessTools.Method(typeof(WorkGiver_Merge), nameof(WorkGiver_Merge.JobOnThing));
 
-		public static void Prefix(Thing t)
+		public static bool Prefix(Thing t, ref Job? __result)
 		{
 			if (t.GetSlotGroup() is null)
+			{
 				RemoveFromListerMergeables(t);
+				__result = null;
+				return false;
+			}
+			return true;
 		}
 
 		private static void RemoveFromListerMergeables(Thing t)