go!!

code/modules/vehicles/mecha/_mecha.dm

@@ -459,7 +459,7 @@
 				transfer_moles = pressure_delta*cabin_air.return_volume()/(cabin_air.return_temperature() * R_IDEAL_GAS_EQUATION)
 				cabin_air.transfer_to(t_air, transfer_moles)
 
-	if(occupants)
+	if(LAZYLEN(occupants))
 		for(var/i in occupants)
 			var/mob/living/occupant = i
 			if(cell)
@@ -908,13 +908,14 @@
 
 ///Handles an actual AI (simple_animal mecha pilot) entering the mech
 /obj/vehicle/sealed/mecha/proc/aimob_enter_mech(mob/living/simple_animal/hostile/syndicate/mecha_pilot/pilot_mob)
-	if(pilot_mob && pilot_mob.Adjacent(src))
-		if(LAZYLEN(occupants))
-			return
-		LAZYADD(occupants, src)
-		pilot_mob.mecha = src
-		pilot_mob.forceMove(src)
-		update_icon()
+	if(!pilot_mob?.Adjacent(src))
+		return
+	if(LAZYLEN(occupants))
+		return
+	LAZYSET(occupants, pilot_mob, NONE)
+	pilot_mob.mecha = src
+	pilot_mob.forceMove(src)
+	update_icon()
 
 ///Handles an actual AI (simple_animal mecha pilot) exiting the mech
 /obj/vehicle/sealed/mecha/proc/aimob_exit_mech(mob/living/simple_animal/hostile/syndicate/mecha_pilot/pilot_mob)

code/modules/vehicles/mecha/combat/durand.dm

@@ -177,7 +177,7 @@ own integrity back to max. Shield is automatically dropped if we run out of powe
 /obj/durand_shield/proc/activate(datum/source, mob/owner, list/signal_args)
 	SIGNAL_HANDLER
 	currentuser = owner
-	if(!chassis?.occupants)
+	if(!LAZYLEN(chassis?.occupants))
 		return
 	if(switching && !signal_args[1])
 		return

code/modules/vehicles/mecha/equipment/mecha_equipment.dm

@@ -41,7 +41,7 @@
 			chassis.selected = null
 		update_chassis_page()
 		log_message("[src] is destroyed.", LOG_MECHA)
-		if(chassis.occupants)
+		if(!LAZYLEN(chassis?.occupants))
 			to_chat(chassis.occupants, "[icon2html(src, chassis.occupants)]<span class='danger'>[src] is destroyed!</span>")
 			playsound(chassis, destroy_sound, 50)
 		if(!detachable) //If we're a built-in nondetachable equipment, let's lock up the slot that we were in.

code/modules/vehicles/mecha/equipment/tools/mining_tools.dm

@@ -173,8 +173,7 @@
 		STOP_PROCESSING(SSfastprocess, src)
 		qdel(src)
 	if(istype(loc, /obj/vehicle/sealed/mecha/working) && scanning_time <= world.time)
-		var/obj/vehicle/sealed/mecha/working/mecha = loc
-		if(!mecha.occupants)
+		if(!LAZYLEN(chassis?.occupants))
 			return
 		scanning_time = world.time + equip_cooldown
 		mineral_scan_pulse(get_turf(src))

code/modules/vehicles/mecha/mecha_defense.dm

@@ -156,7 +156,7 @@
 		for(var/occus in occupants)
 			var/mob/living/occupant = occus
 			occupant.update_mouse_pointer()
-	if(!equipment_disabled && occupants) //prevent spamming this message with back-to-back EMPs
+	if(!equipment_disabled && LAZYLEN(occupants)) //prevent spamming this message with back-to-back EMPs
 		to_chat(occupants, "<span=danger>Error -- Connection to equipment control unit has been lost.</span>")
 	addtimer(CALLBACK(src, TYPE_PROC_REF(/obj/vehicle/sealed/mecha, restore_equipment)), 3 SECONDS, TIMER_UNIQUE | TIMER_OVERRIDE)
 	equipment_disabled = 1