Fixes random failure in cleanbot pathing (#71660)

## About The Pull Request

Ok so like, it used to be we would hand back our path immediately after
get_path_to

What's happening now is the path is completed, and THEN we have to wait
a tick before getting it back
So between the path finishing and our UNTIL resuming, our mob could be
deleted

This resolves that issue, wrapping the UNTIL in some qdeleted checks to
return a failure response

## Why It's Good For The Game

Fixes #71628. Also fixes #71493, ~~quit using = to set the path it's a
setter for a reason 🗞️~~ I FUCKED UP JPS SHOULD RETURN AN EMPTY LIST ON
FAILURE NOT NULL

code/__HELPERS/path.dm

@@ -25,11 +25,11 @@
 	// We're guarenteed that list will be the first list in pathfinding_finished's argset because of how callback handles the arguments list
 	var/datum/callback/await = CALLBACK(GLOBAL_PROC, /proc/pathfinding_finished, path)
 	if(!SSpathfinder.pathfind(caller, end, max_distance, mintargetdist, id, simulated_only, exclude, skip_first, diagonal_safety, await))
-		return null
+		return list()
 
 	UNTIL(length(path))
-	if(length(path) == 1 && path[1] == null) // It's trash, just hand back null to make it easy
-		return null
+	if(length(path) == 1 && path[1] == null || (QDELETED(caller) || QDELETED(end))) // It's trash, just hand back null to make it easy
+		return list()
 	return path
 
 /// Uses funny pass by reference bullshit to take the path created by pathfinding, and insert it into a return list

code/modules/mob/living/simple_animal/bot/bot.dm

@@ -1039,7 +1039,7 @@ Pass a positive integer as an argument to override a bot's default speed.
 
 	var/list/path_images = active_hud_list[DIAG_PATH_HUD]
 	QDEL_LIST(path_images)
-	if(newpath)
+	if(length(newpath))
 		var/mutable_appearance/path_image = new /mutable_appearance()
 		path_image.icon = path_image_icon
 		path_image.icon_state = path_image_icon_state

code/modules/mob/living/simple_animal/bot/cleanbot.dm

@@ -298,7 +298,6 @@
 			if(length(path) == 0)
 				add_to_ignore(target)
 				target = null
-				path = list()
 
 		if(path.len > 0 && target)
 			if(!bot_move(path[path.len]))

code/modules/mob/living/simple_animal/parrot.dm

@@ -654,7 +654,7 @@ GLOBAL_LIST_INIT(strippable_parrot_items, create_strippable_list(list(
 					item = I
 					break
 		if(item)
-			if(!get_path_to(src, item)) // WHY DO WE DISREGARD THE PATH AHHHHHH
+			if(!length(get_path_to(src, item))) // WHY DO WE DISREGARD THE PATH AHHHHHH
 				item = null
 				continue
 			return item