Initial fixes from testing

code/modules/mob/living/carbon/xenomorph/castes/Carrier.dm

@@ -15,6 +15,7 @@
 	speed = XENO_SPEED_TIER_4
 
 	available_strains = list(/datum/xeno_strain/eggsac)
+	behavior_delegate_type = /datum/behavior_delegate/carrier_base
 
 	evolution_allowed = FALSE
 	deevolves_to = list(XENO_CASTE_DRONE)
@@ -78,8 +79,6 @@
 		/mob/living/carbon/xenomorph/proc/set_hugger_reserve_for_morpher,
 	)
 
-	behavior_delegate = /datum/behavior_delegate/carrier_base
-
 	icon_xenonid = 'icons/mob/xenonids/carrier.dmi'
 
 	weed_food_icon = 'icons/mob/xenos/weeds_64x64.dmi'

code/modules/mob/living/carbon/xenomorph/castes/Facehugger.dm

@@ -10,6 +10,7 @@
 	speed = XENO_SPEED_TIER_8
 
 	available_strains = list(/datum/xeno_strain/watcher)
+	behavior_delegate_type = /datum/behavior_delegate/facehugger_base
 
 	evolution_allowed = FALSE
 	can_be_revived = FALSE
@@ -58,8 +59,6 @@
 		/mob/living/carbon/xenomorph/proc/vent_crawl,
 	)
 
-	behavior_delegate = /datum/behavior_delegate/facehugger_base
-
 	icon_xeno = 'icons/mob/xenos/facehugger.dmi'
 	icon_xenonid = 'icons/mob/xenonids/facehugger.dmi'
 

code/modules/mob/living/carbon/xenomorph/strains/castes/drone/gardener.dm

@@ -363,9 +363,6 @@
 
 	var/mutable_appearance/fruit_sac_overlay_icon
 
-/datum/behavior_delegate/drone_gardener/add_to_xeno()
-	on_update_icons()
-
 /datum/behavior_delegate/drone_gardener/on_update_icons()
 	if(!fruit_sac_overlay_icon)
 		fruit_sac_overlay_icon = mutable_appearance('icons/mob/xenos/drone_strain_overlays.dmi', "Gardener Drone Walking")

code/modules/mob/living/carbon/xenomorph/strains/xeno_strain.dm

@@ -102,6 +102,10 @@
 	if(!length(caste.available_strains) || !check_state(TRUE))
 		return FALSE
 
+	if(strain)
+		to_chat(src, SPAN_WARNING("We have already chosen a strain."))
+		return FALSE
+
 	if(is_ventcrawling)
 		to_chat(src, SPAN_WARNING("This place is too constraining to take a strain."))
 		return FALSE