OpenDream Cleanup Pass - Unused Vars (#71428)

## About The Pull Request

OpenDream (@Altoids1 specifically) discovered that BYOND will not throw
an unused variable warning if its type doesn't exist. So this removes
those from TG.

Co-authored-by: ike709 <ike709@github.com>

code/datums/components/crafting/crafting.dm

@@ -51,7 +51,6 @@
 
 	var/cur_category = CAT_NONE
 	var/cur_subcategory = CAT_NONE
-	var/datum/action/innate/crafting/button
 	var/display_craftable_only = FALSE
 	var/display_compact = TRUE
 

code/modules/mob/dead/observer/observer.dm

@@ -23,7 +23,6 @@ GLOBAL_VAR_INIT(observer_default_invisibility, INVISIBILITY_OBSERVER)
 	light_on = FALSE
 	shift_to_open_context_menu = FALSE
 	var/can_reenter_corpse
-	var/datum/hud/living/carbon/hud = null // hud
 	var/bootime = 0
 	var/started_as_observer //This variable is set to 1 when you enter the game as an observer.
 							//If you died in the game and are a ghost - this will remain as null.

code/modules/mob/living/simple_animal/hostile/jungle/seedling.dm

@@ -34,7 +34,6 @@
 	stat_attack = HARD_CRIT
 	move_resist = MOVE_FORCE_EXTREMELY_STRONG
 	var/combatant_state = SEEDLING_STATE_NEUTRAL
-	var/obj/seedling_weakpoint/weak_point
 	var/mob/living/beam_debuff_target
 	var/solar_beam_identifier = 0