fixes a tgui input gc issue (#25160)

code/modules/tgui/tgui_input/number_input.dm

@@ -66,6 +66,8 @@
 	var/start_time
 	/// The lifespan of the number input, after which the window will close and delete itself.
 	var/timeout
+	/// The attached timer that handles this objects timeout deletion
+	var/deletion_timer
 	/// The title of the TGUI window
 	var/title
 	/// The TGUI UI state that will be returned in ui_state(). Default: always_state
@@ -83,7 +85,7 @@
 	if(timeout)
 		src.timeout = timeout
 		start_time = world.time
-		QDEL_IN(src, timeout)
+		deletion_timer = QDEL_IN(src, timeout)
 
 	/// Checks for empty numbers - bank accounts, etc.
 	if(max_value == 0)
@@ -101,6 +103,7 @@
 /datum/tgui_input_number/Destroy(force)
 	SStgui.close_uis(src)
 	state = null
+	deltimer(deletion_timer)
 	return ..()
 
 /**