[MIRROR] Fixes stowing suit storage jetpacks when retracting modsuit chestplates [MDB IGNORE] (#21888)

* Fixes stowing suit storage jetpacks when retracting modsuit chestplates (#75844)

## About The Pull Request

This is a bizare bug I discovered while trying to develop another
feature, so let's just get into the reproduction steps:
- Wear a modsuit and extend it's parts
- Put a jetpack in the suit storage slot and turn it on. Currently, the
only jetpack that fits in the storage slot on TG is the captain's
jetpack.
- While the jetpack is activated, deactivate your modsuit using the UI,
which stows the jetpack into your storage module automatically.
- This fails to unregister some signal thing because it can't find the
user.

My fix *could* be shitcode, so any feedback would be appreciated.

Jetpack activation and deactivation signals now pass a user.
`/datum/component/jetpack/proc/activate(datum/source, mob/user)`
`/datum/component/jetpack/proc/deactivate(datum/source, mob/user)`

Some jetpack `pre_move_react` thing now has a check to see if it's
argument is null.
```
if(!trail)
	return FALSE
```

## Why It's Good For The Game

Stops a crash/runtime.
## Changelog
🆑 stonetear
fix: jetpack signals now pass a user argument. This fixes an error when
automatically stowing a captain jetpack into your modsuit.
/🆑

* Fixes stowing suit storage jetpacks when retracting modsuit chestplates

---------

Co-authored-by: Stonetear <89315023+Stonetear@users.noreply.github.com>

code/datums/components/jetpack.dm

@@ -78,27 +78,25 @@
 	trail.auto_process = FALSE
 	trail.set_up(moving)
 
-/datum/component/jetpack/proc/activate(datum/source)
+/datum/component/jetpack/proc/activate(datum/source, mob/user)
 	SIGNAL_HANDLER
-	var/mob/moving = get_mover.Invoke()
-	if(!thrust(moving))
+	if(!thrust(user))
 		return return_flag
 	trail.start()
-	RegisterSignal(moving, COMSIG_MOVABLE_MOVED, PROC_REF(move_react))
-	RegisterSignal(moving, COMSIG_MOVABLE_PRE_MOVE, PROC_REF(pre_move_react))
-	RegisterSignal(moving, COMSIG_MOVABLE_SPACEMOVE, PROC_REF(spacemove_react))
-	RegisterSignal(moving, COMSIG_MOVABLE_DRIFT_VISUAL_ATTEMPT, PROC_REF(block_starting_visuals))
-	RegisterSignal(moving, COMSIG_MOVABLE_DRIFT_BLOCK_INPUT, PROC_REF(ignore_ending_block))
+	RegisterSignal(user, COMSIG_MOVABLE_MOVED, PROC_REF(move_react))
+	RegisterSignal(user, COMSIG_MOVABLE_PRE_MOVE, PROC_REF(pre_move_react))
+	RegisterSignal(user, COMSIG_MOVABLE_SPACEMOVE, PROC_REF(spacemove_react))
+	RegisterSignal(user, COMSIG_MOVABLE_DRIFT_VISUAL_ATTEMPT, PROC_REF(block_starting_visuals))
+	RegisterSignal(user, COMSIG_MOVABLE_DRIFT_BLOCK_INPUT, PROC_REF(ignore_ending_block))
 
-/datum/component/jetpack/proc/deactivate(datum/source)
+/datum/component/jetpack/proc/deactivate(datum/source, mob/user)
 	SIGNAL_HANDLER
-	var/mob/moving = get_mover.Invoke()
-	if(moving)
-		UnregisterSignal(moving, COMSIG_MOVABLE_MOVED)
-		UnregisterSignal(moving, COMSIG_MOVABLE_PRE_MOVE)
-		UnregisterSignal(moving, COMSIG_MOVABLE_SPACEMOVE)
-		UnregisterSignal(moving, COMSIG_MOVABLE_DRIFT_VISUAL_ATTEMPT)
-		UnregisterSignal(moving, COMSIG_MOVABLE_DRIFT_BLOCK_INPUT)
+	if(user)
+		UnregisterSignal(user, COMSIG_MOVABLE_MOVED)
+		UnregisterSignal(user, COMSIG_MOVABLE_PRE_MOVE)
+		UnregisterSignal(user, COMSIG_MOVABLE_SPACEMOVE)
+		UnregisterSignal(user, COMSIG_MOVABLE_DRIFT_VISUAL_ATTEMPT)
+		UnregisterSignal(user, COMSIG_MOVABLE_DRIFT_BLOCK_INPUT)
 	QDEL_NULL(trail) //delete AFTER unregistering the mob, otherwise you'll get runtimes.
 
 /datum/component/jetpack/proc/move_react(mob/user)
@@ -118,6 +116,8 @@
 
 /datum/component/jetpack/proc/pre_move_react(mob/user)
 	SIGNAL_HANDLER
+	if(!trail)
+		return FALSE
 	trail.oldposition = get_turf(user)
 
 /datum/component/jetpack/proc/spacemove_react(mob/user, movement_dir, continuous_move)

code/game/objects/items/tanks/jetpack.dm

@@ -86,7 +86,7 @@
 	icon_state = "[initial(icon_state)][on ? "-on" : ""]"
 
 /obj/item/tank/jetpack/proc/turn_on(mob/user)
-	if(SEND_SIGNAL(src, COMSIG_JETPACK_ACTIVATED) & JETPACK_ACTIVATION_FAILED)
+	if(SEND_SIGNAL(src, COMSIG_JETPACK_ACTIVATED, user) & JETPACK_ACTIVATION_FAILED)
 		return FALSE
 	on = TRUE
 	update_icon(UPDATE_ICON_STATE)
@@ -95,7 +95,7 @@
 	return TRUE
 
 /obj/item/tank/jetpack/proc/turn_off(mob/user)
-	SEND_SIGNAL(src, COMSIG_JETPACK_DEACTIVATED)
+	SEND_SIGNAL(src, COMSIG_JETPACK_DEACTIVATED, user)
 	on = FALSE
 	set_stabilizers(FALSE)
 	update_icon(UPDATE_ICON_STATE)