Merge branch 'master' into development

# Conflicts:
#	maps/aurora/aurora-1_centcomm.dmm

code/modules/hydroponics/spreading/spreading.dm

@@ -169,6 +169,8 @@
 			last_biolum = null
 
 /obj/effect/plant/proc/refresh_icon()
+	if(!growth_threshold)
+		growth_threshold = max_health/seed.growth_stages
 	var/growth = min(max_growth,round(health/growth_threshold))
 	var/at_fringe = get_dist(src,parent)
 	if(spread_distance > 5)

code/modules/hydroponics/spreading/spreading_growth.dm

@@ -17,7 +17,7 @@
 		if((locate(/obj/effect/plant) in floor.contents) || (locate(/obj/effect/dead_plant) in floor.contents) )
 			continue
 		if(floor.density)
-			if(seed.chems["pacid"])
+			if(seed && seed.chems["pacid"])
 				addtimer(CALLBACK(floor, /atom/.proc/ex_act, 3), rand(5, 25))
 			continue
 		if(!Adjacent(floor) || !floor.Enter(src))