Add property requirements to safe traits

OpenRA.Mods.Common/Traits/SupportPowers/GrantUpgradePower.cs

@@ -19,7 +19,7 @@ namespace OpenRA.Mods.Common.Traits
 {
 	class GrantUpgradePowerInfo : SupportPowerInfo
 	{
-		[UpgradeGrantedReference]
+		[UpgradeGrantedReference, FieldLoader.Require]
 		[Desc("The upgrades to apply.")]
 		public readonly string[] Upgrades = { };
 

OpenRA.Mods.Common/Traits/SupportPowers/SpawnActorPower.cs

@@ -12,12 +12,14 @@ using OpenRA.Effects;
 using OpenRA.Mods.Common.Activities;
 using OpenRA.Mods.Common.Effects;
 using OpenRA.Primitives;
+using OpenRA.Traits;
 
 namespace OpenRA.Mods.Common.Traits
 {
 	[Desc("Spawns an actor that stays for a limited amount of time.")]
 	public class SpawnActorPowerInfo : SupportPowerInfo
 	{
+		[ActorReference, FieldLoader.Require]
 		[Desc("Actor to spawn.")]
 		public readonly string Actor = null;