Allow harvester definitions to exist on non-mobile actors

OpenRA.Mods.Common/Traits/BotModules/HarvesterBotModule.cs

@@ -51,7 +51,7 @@ public HarvesterTraitWrapper(Actor actor)
 				Actor = actor;
 				Harvester = actor.Trait<Harvester>();
 				Parachutable = actor.TraitOrDefault<Parachutable>();
-				Mobile = actor.Trait<Mobile>();
+				Mobile = actor.TraitOrDefault<Mobile>();
 			}
 		}
 
@@ -110,6 +110,9 @@ void IBotTick.BotTick(IBot bot)
 			// Find idle harvesters and give them orders:
 			foreach (var h in harvesters)
 			{
+				if (h.Value.Mobile == null)
+					continue;
+
 				if (!h.Key.IsIdle)
 				{
 					// Ignore this actor if FindAndDeliverResources is working fine or it is performing a different activity

OpenRA.Mods.Common/Traits/Harvester.cs

@@ -18,7 +18,7 @@
 
 namespace OpenRA.Mods.Common.Traits
 {
-	public class HarvesterInfo : DockClientBaseInfo, Requires<MobileInfo>, Requires<IStoresResourcesInfo>, IRulesetLoaded
+	public class HarvesterInfo : DockClientBaseInfo, Requires<IStoresResourcesInfo>, IRulesetLoaded
 	{
 		[Desc("Docking type")]
 		public readonly BitSet<DockType> Type = new("Unload");
@@ -90,7 +90,7 @@ void IRulesetLoaded<ActorInfo>.RulesetLoaded(Ruleset rules, ActorInfo info)
 	public class Harvester : DockClientBase<HarvesterInfo>, IIssueOrder, IResolveOrder, IOrderVoice,
 		ISpeedModifier, ISync, INotifyCreated
 	{
-		readonly Mobile mobile;
+		Mobile mobile;
 		readonly IResourceLayer resourceLayer;
 		readonly ResourceClaimLayer claimLayer;
 		readonly IStoresResources[] storesResources;
@@ -104,18 +104,18 @@ public class Harvester : DockClientBase<HarvesterInfo>, IIssueOrder, IResolveOrd
 		public Harvester(Actor self, HarvesterInfo info)
 			: base(self, info)
 		{
-			mobile = self.Trait<Mobile>();
 			storesResources = self.TraitsImplementing<IStoresResources>().Where(sr => info.Resources.Any(r => sr.HasType(r))).ToArray();
 			resourceLayer = self.World.WorldActor.Trait<IResourceLayer>();
 			claimLayer = self.World.WorldActor.Trait<ResourceClaimLayer>();
 		}
 
 		protected override void Created(Actor self)
 		{
+			mobile = self.TraitOrDefault<Mobile>();
 			UpdateCondition(self);
 
 			// Note: This is queued in a FrameEndTask because otherwise the activity is dropped/overridden while moving out of a factory.
-			if (Info.SearchOnCreation)
+			if (Info.SearchOnCreation && mobile != null)
 				self.World.AddFrameEndTask(w => self.QueueActivity(new FindAndDeliverResources(self)));
 
 			base.Created(self);
@@ -218,7 +218,7 @@ IEnumerable<IOrderTargeter> IIssueOrder.Orders
 		{
 			get
 			{
-				if (IsTraitDisabled)
+				if (IsTraitDisabled || mobile == null)
 					yield break;
 
 				yield return new HarvestOrderTargeter();
@@ -235,15 +235,15 @@ Order IIssueOrder.IssueOrder(Actor self, IOrderTargeter order, in Target target,
 
 		string IOrderVoice.VoicePhraseForOrder(Actor self, Order order)
 		{
-			if (order.OrderString == "Harvest")
+			if (order.OrderString == "Harvest" && mobile != null)
 				return Info.HarvestVoice;
 
 			return null;
 		}
 
 		void IResolveOrder.ResolveOrder(Actor self, Order order)
 		{
-			if (order.OrderString == "Harvest")
+			if (order.OrderString == "Harvest" && mobile != null)
 			{
 				CPos loc;
 				if (order.Target.Type != TargetType.Invalid)