[MIRROR] Fixes being permanently attached to tram (#2796)

* Fixes being permanently attached to tram (#83606)

## About The Pull Request

Verifies transport contents at time of tram departure, removing any
invalid movables

Fixes tgstation/tgstation#77722

## Why It's Good For The Game

Movables no longer get invisibly, permanently attached to the tram in
rare event transport moves before contents are updated.

## Changelog

:cl: LT3
fix: Fixed bug where players could be invisibly attached to the tram
forever
/:cl:

* Fixes being permanently attached to tram

---------

Co-authored-by: lessthanthree <[email protected]>
Co-authored-by: NovaBot13 <[email protected]>

code/modules/transport/tram/tram_controller.dm

@@ -250,6 +250,7 @@
 	for(var/obj/structure/transport/linear/tram/transport_module as anything in transport_modules) //only thing everyone needs to know is the new location.
 		if(transport_module.travelling) //wee woo wee woo there was a double action queued. damn multi tile structs
 			return //we don't care to undo cover_locked controls, though, as that will resolve itself
+		transport_module.verify_transport_contents()
 		transport_module.glide_size_override = DELAY_TO_GLIDE_SIZE(speed_limiter)
 		transport_module.set_travelling(TRUE)
 

code/modules/transport/transport_module.dm

@@ -165,6 +165,12 @@
 
 				initial_contents += new_initial_contents
 
+///verify the movables in our list of contents are actually on our loc
+/obj/structure/transport/linear/proc/verify_transport_contents()
+	for(var/atom/movable/movable_contents as anything in transport_contents)
+		if(!(movable_contents.loc in locs))
+			remove_item_from_transport(movable_contents)
+
 ///signal handler for COMSIG_MOVABLE_UPDATE_GLIDE_SIZE: when a movable in transport_contents changes its glide_size independently.
 ///adds that movable to a lazy list, movables in that list have their glide_size updated when the tram next moves
 /obj/structure/transport/linear/proc/on_changed_glide_size(atom/movable/moving_contents, new_glide_size)