Fixed some runtime errors.

git-svn-id: http://tgstation13.googlecode.com/svn/trunk@1276 316c924e-a436-60f5-8080-3fe189b3f50e

code/WorkInProgress/Chemistry-Holder.dm

@@ -58,7 +58,7 @@ datum
 				return the_id
 
 			trans_to(var/obj/target, var/amount=1, var/multiplier=1, var/preserve_data=1)//if preserve_data=0, the reagents data will be lost. Usefull if you use data for some strange stuff and don't want it to be transferred.
-				if (!target)
+				if (!target || src.total_volume<=0)
 					return
 				var/datum/reagents/R = target.reagents
 				amount = min(min(amount, src.total_volume), R.maximum_volume-R.total_volume)