Drag-n-drop hotfix (#4468)

# About the pull request

Should fix some oversights with the skill nesting system.

# Explain why it's good for the game

Bug bad


# Testing Photographs and Procedure
<details>
<summary>Screenshots & Videos</summary>

Put screenshots and videos here with an empty line between the
screenshots and the `<details>` tags.

</details>


# Changelog

:cl: Morrow
fix: Fixed drag-n-drop nesting opening
/:cl:

code/game/objects/items/storage/storage.dm

@@ -81,19 +81,7 @@
 	return ..()
 
 /obj/item/storage/proc/handle_mmb_open(mob/user)
-	if(!required_skill_for_nest_opening || !required_skill_level_for_nest_opening)
-		open(user)
-		return
-
-	if(!istype(loc, /obj/item/storage))
-		open(user)
-		return
-
-	if(user?.skills.get_skill_level(required_skill_for_nest_opening) >= required_skill_level_for_nest_opening)
-		open(user)
-		return
-
-	to_chat(user, SPAN_NOTICE("You can't seem to open [src] while it is in [loc]."))
+	open(user)
 
 /obj/item/storage/proc/return_inv()
 	RETURN_TYPE(/list)
@@ -171,6 +159,12 @@
 /obj/item/storage/proc/open(mob/user)
 	if(user.s_active == src) //Spam prevention.
 		return
+
+	if(istype(loc, /obj/item/storage) && required_skill_for_nest_opening)
+		if(!user || user.skills?.get_skill_level(required_skill_for_nest_opening) < required_skill_level_for_nest_opening)
+			to_chat(user, SPAN_NOTICE("You can't seem to open [src] while it is in [loc]."))
+			return
+
 	if(!opened)
 		orient2hud()
 		opened = 1
@@ -419,7 +413,7 @@ var/list/global/item_storage_box_cache = list()
 /obj/item/storage/proc/can_hold_type(type_to_hold, mob/user)
 	if(length(can_hold_skill))
 		for(var/can_hold_skill_typepath in can_hold_skill)
-			if(ispath(type_to_hold, can_hold_skill_typepath) && user?.skills.get_skill_level(can_hold_skill[can_hold_skill_typepath][SKILL_TYPE_INDEX]) >= can_hold_skill[can_hold_skill_typepath][SKILL_LEVEL_INDEX])
+			if(ispath(type_to_hold, can_hold_skill_typepath) && user.skills?.get_skill_level(can_hold_skill[can_hold_skill_typepath][SKILL_TYPE_INDEX]) >= can_hold_skill[can_hold_skill_typepath][SKILL_LEVEL_INDEX])
 				return TRUE
 		if(can_hold_skill_only)
 			return FALSE