Fixes 2 gun runtime sources

code/datums/components/autofire/autofire.dm

@@ -123,19 +123,19 @@
 		if(GUN_FIREMODE_BURSTFIRE)
 			shots_fired++
 			if(shots_fired == burst_shots_to_fire)
-				callback_bursting.Invoke(FALSE)
-				callback_display_ammo.Invoke()
+				callback_bursting?.Invoke(FALSE)
+				callback_display_ammo?.Invoke()
 				bursting = FALSE
 				stop_firing()
 				if(have_to_reset_at_burst_end)//We failed to reset because we were bursting, we do it now
-					callback_reset_fire.Invoke()
+					callback_reset_fire?.Invoke()
 					have_to_reset_at_burst_end = FALSE
 				return
-			callback_bursting.Invoke(TRUE)
+			callback_bursting?.Invoke(TRUE)
 			bursting = TRUE
 			next_fire = world.time + burstfire_shot_delay
 		if(GUN_FIREMODE_AUTOMATIC)
-			callback_set_firing.Invoke(TRUE)
+			callback_set_firing?.Invoke(TRUE)
 			next_fire = world.time + (auto_fire_shot_delay * automatic_delay_mult)
 		if(GUN_FIREMODE_SEMIAUTO)
 			return

code/modules/cm_marines/smartgun_mount.dm

@@ -475,8 +475,6 @@
 	var/autofire_slow_mult = 1
 	/// If the gun is currently burst firing
 	VAR_PROTECTED/burst_firing = FALSE
-	/// If the gun is currently auto firing
-	VAR_PROTECTED/auto_firing = FALSE
 	/// If the gun should display its ammo count
 	var/display_ammo = TRUE
 	/// How many degrees in each direction the gun should be able to fire
@@ -514,13 +512,14 @@
 	ammo = GLOB.ammo_list[ammo] //dunno how this works but just sliding this in from sentry-code.
 	burst_scatter_mult = SCATTER_AMOUNT_TIER_7
 	update_icon()
-	AddComponent(/datum/component/automatedfire/autofire, fire_delay, burst_fire_delay, burst_amount, gun_firemode, autofire_slow_mult, CALLBACK(src, PROC_REF(set_burst_firing)), CALLBACK(src, PROC_REF(reset_fire)), CALLBACK(src, PROC_REF(try_fire)), CALLBACK(src, PROC_REF(display_ammo)), CALLBACK(src, PROC_REF(set_auto_firing)))
+	AddComponent(/datum/component/automatedfire/autofire, fire_delay, burst_fire_delay, burst_amount, gun_firemode, autofire_slow_mult, CALLBACK(src, PROC_REF(set_burst_firing)), CALLBACK(src, PROC_REF(reset_fire)), CALLBACK(src, PROC_REF(try_fire)), CALLBACK(src, PROC_REF(display_ammo)))
 
-/obj/structure/machinery/m56d_hmg/Destroy() //Make sure we pick up our trash.
-	if(operator)
-		operator.unset_interaction()
+/obj/structure/machinery/m56d_hmg/Destroy(force) //Make sure we pick up our trash.
+	operator?.unset_interaction()
+	operator = null
+	QDEL_NULL(in_chamber)
 	STOP_PROCESSING(SSobj, src)
-	. = ..()
+	return ..()
 
 /obj/structure/machinery/m56d_hmg/get_examine_text(mob/user) //Let us see how much ammo we got in this thing.
 	. = ..()
@@ -751,6 +750,8 @@
 	update_icon() //final safeguard.
 
 /obj/structure/machinery/m56d_hmg/proc/try_fire()
+	if(!operator)
+		return
 	if(!rounds)
 		to_chat(operator, SPAN_WARNING("<b>*click*</b>"))
 		playsound(src, 'sound/weapons/gun_empty.ogg', 25, 1, 5)
@@ -855,6 +856,7 @@
 
 /obj/structure/machinery/m56d_hmg/on_unset_interaction(mob/user)
 	flags_atom &= ~RELAY_CLICK
+	SEND_SIGNAL(src, COMSIG_GUN_INTERRUPT_FIRE)
 	user.status_flags &= ~IMMOBILE_ACTION
 	user.visible_message(SPAN_NOTICE("[user] lets go of \the [src]."),SPAN_NOTICE("You let go of \the [src], letting the gun rest."))
 	user.unfreeze()
@@ -947,7 +949,6 @@
 /// Clean up the target, shots fired, and other things related to when you stop firing
 /obj/structure/machinery/m56d_hmg/proc/reset_fire()
 	set_target(null)
-	set_auto_firing(FALSE)
 	shots_fired = 0
 
 ///Set the target and take care of hard delete
@@ -960,10 +961,6 @@
 	if(target)
 		RegisterSignal(target, COMSIG_PARENT_QDELETING, PROC_REF(clean_target))
 
-/// Setter for auto_firing
-/obj/structure/machinery/m56d_hmg/proc/set_auto_firing(auto = FALSE)
-	auto_firing = auto
-
 /// Print how much ammo is left to chat
 /obj/structure/machinery/m56d_hmg/proc/display_ammo()
 	if(!operator)

code/modules/projectiles/gun.dm

@@ -1963,6 +1963,7 @@ not all weapons use normal magazines etc. load_into_chamber() itself is designed
 
 /// Setter proc for fa_firing
 /obj/item/weapon/gun/proc/set_auto_firing(auto = FALSE)
+	SIGNAL_HANDLER
 	fa_firing = auto
 
 /// Getter for gun_user

code/modules/projectiles/guns/lever_action.dm

@@ -405,9 +405,9 @@ their unique feature is that a direct hit will buff your damage and firerate
 
 /obj/item/weapon/gun/lever_action/xm88/wield(mob/user)
 	. = ..()
-
-	RegisterSignal(src, COMSIG_ITEM_ZOOM, PROC_REF(scope_on))
-	RegisterSignal(src, COMSIG_ITEM_UNZOOM, PROC_REF(scope_off))
+	if(.)
+		RegisterSignal(src, COMSIG_ITEM_ZOOM, PROC_REF(scope_on))
+		RegisterSignal(src, COMSIG_ITEM_UNZOOM, PROC_REF(scope_off))
 
 /obj/item/weapon/gun/lever_action/xm88/proc/scope_on(atom/source, mob/current_user)
 	SIGNAL_HANDLER