Merge pull request #2674 from yogstation13/upstream-merge-40415

[MIRROR] Ice sliding related fixes.

code/datums/forced_movement.dm

@@ -51,6 +51,9 @@
 		last_processed = world.time
 
 /datum/forced_movement/proc/TryMove(recursive = FALSE)
+	if(QDELETED(src)) //Our previous step caused deletion of this datum
+		return
+
 	var/atom/movable/vic = victim	//sanic
 	var/atom/tar = target
 

code/game/turfs/open.dm

@@ -231,6 +231,7 @@
 			C.accident(I)
 
 		var/olddir = C.dir
+		C.moving_diagonally = 0 //If this was part of diagonal move slipping will stop it.
 		if(!(lube & SLIDE_ICE))
 			C.Knockdown(knockdown_amount)
 			C.stop_pulling()
@@ -244,6 +245,8 @@
 		if(lube&SLIDE)
 			new /datum/forced_movement(C, get_ranged_target_turf(C, olddir, 4), 1, FALSE, CALLBACK(C, /mob/living/carbon/.proc/spin, 1, 1))
 		else if(lube&SLIDE_ICE)
+			if(C.force_moving) //If we're already slipping extend it
+				qdel(C.force_moving)
 			new /datum/forced_movement(C, get_ranged_target_turf(C, olddir, 1), 1, FALSE)	//spinning would be bad for ice, fucks up the next dir
 		return 1