Spider tweaks and Mob pulling (#17782)

* Spider tweaks and Mob pulling

Added a small amount of weaken to spider warning bites to knock people over.
Added a new variable to mobs that can prevent them from being pulled when alive, currently only applies to the spiders.
Fixed an issue where spiders would sometimes try to inject poison where they couldn't and runtime.

* Invert var

code/modules/mob/living/simple_mob/subtypes/animal/giant_spider/_giant_spider.dm

@@ -127,6 +127,8 @@
 	var/warning_warmup = 2 SECONDS // How long the leap telegraphing is.
 	var/warning_sound = 'sound/weapons/spiderlunge.ogg'
 
+	no_pull_when_living = TRUE
+
 
 /mob/living/simple_mob/animal/giant_spider/Initialize(mapload)
 	. = ..()
@@ -204,7 +206,8 @@
 		break
 
 	if(victim)
-		A.reagents.add_reagent(REAGENT_ID_WARNINGTOXIN, poison_per_bite)
+		victim.reagents.add_reagent(REAGENT_ID_WARNINGTOXIN, poison_per_bite)
+		victim.AdjustWeakened(2)
 		victim.visible_message(span_danger("\The [src] has bitten \the [victim]!"))
 		to_chat(victim, span_critical("\The [src] bites you and retreats!"))
 		. = TRUE