fix(fueltank): empty tank can no longer be blown up

#12838

code/modules/reagents/reagent_dispenser.dm

@@ -181,7 +181,14 @@
 			  SPAN("notice", "You rig [W] to \the [src].")
 			)
 			update_icon()
+
 	else if(W.get_temperature_as_from_ignitor())
+		if (reagents.total_volume == 0)
+			user.visible_message(
+		 	 SPAN("danger", "[user] puts [W] to [src]."),
+		 	 SPAN("danger", "You put \the [W] to \the [src] and nothing happens.")
+			)
+			return
 		log_and_message_admins("triggered a fueltank explosion with [W].")
 		user.visible_message(
 		  SPAN("danger", "[user] puts [W] to [src]!"),
@@ -215,7 +222,19 @@
 		if(!istype(Proj ,/obj/item/projectile/beam/lasertag) && !istype(Proj ,/obj/item/projectile/beam/practice) )
 			explode()
 
-/obj/structure/reagent_dispensers/fueltank/ex_act()
+/obj/structure/reagent_dispensers/fueltank/ex_act(severity)
+	switch(severity)
+		if(1.0)
+			qdel(src)
+			return
+		if(2.0)
+			if (prob(50))
+				qdel(src)
+				return
+		if(3.0)
+			if (prob(5))
+				qdel(src)
+				return
 	explode()
 
 /obj/structure/reagent_dispensers/fueltank/proc/explode()
@@ -225,6 +244,8 @@
 		explosion(src.loc,0,1,3,sfx_to_play=SFX_EXPLOSION_FUEL)
 	else if (reagents.total_volume > 50)
 		explosion(src.loc,-1,1,2,sfx_to_play=SFX_EXPLOSION_FUEL)
+	else if (reagents.total_volume == 0)
+		return
 	if(src)
 		qdel(src)