The 515 MegaPR early downport (#7783)

Co-authored-by: Selis <selis@xynolabs.com>
Co-authored-by: Selis <sirlionfur@hotmail.de>
Co-authored-by: Kashargul <144968721+Kashargul@users.noreply.github.com>
Co-authored-by: SatinIsle <thesatinisle@gmail.com>
Co-authored-by: Heroman <alesha3000@list.ru>
Co-authored-by: Casey <a.roaming.shadow@gmail.com>
Co-authored-by: Raeschen <rycoop29@gmail.com>

code/controllers/subsystems/overlays.dm

@@ -77,23 +77,31 @@ SUBSYSTEM_DEF(overlays)
 	var/list/result = list()
 	var/icon/icon = subject.icon
 	for (var/atom/entry as anything in sources)
-		if (!entry)
-			continue
-		else if (istext(entry))
-			result += GetStateAppearance(icon, entry)
-		else if (isicon(entry))
-			result += GetIconAppearance(entry)
-		else
-			if (isloc(entry))
-				if (entry.flags & OVERLAY_QUEUED)
-					entry.ImmediateOverlayUpdate()
-			if (!ispath(entry))
-				result += entry.appearance
-			else
-				var/image/image = entry
-				result += image.appearance
+		AppearanceListEntry(entry, result, icon)
 	return result
 
+//Fixes runtime with overlays present in 515
+/datum/controller/subsystem/overlays/proc/AppearanceListEntry(var/atom/entry,var/list/result,var/icon/icon)
+	if (!entry)
+		return
+	else if(islist(entry))
+		var/list/entry_list = entry
+		for(var/entry_item in entry_list)
+			AppearanceListEntry(entry_item)
+	else if (istext(entry))
+		result += GetStateAppearance(icon, entry)
+	else if (isicon(entry))
+		result += GetIconAppearance(entry)
+	else
+		if (isloc(entry))
+			if (entry.flags & OVERLAY_QUEUED)
+				entry.ImmediateOverlayUpdate()
+		if (!ispath(entry))
+			if(entry.appearance)
+				result += entry.appearance
+		else
+			var/image/image = entry
+			result += image.appearance
 
 /// Enqueues the atom for an overlay update if not already queued
 /atom/proc/QueueOverlayUpdate()