Adds a warning and single retry to byond membership lookup (#86765)

## About The Pull Request

A few people are having issues getting byond membership features
disabled even though they're a byond member. This is *likely* due to
byond server troubles, and according to lummox the lookup proc should
return null when a connection issue happens. So I've put some handling
in there for that case as well as a single retry.

🆑
fix: Byond membership lookup should now warn you when it fails due to a
connection failure.
/🆑

code/modules/client/preferences.dm

@@ -105,9 +105,8 @@ GLOBAL_LIST_EMPTY(preferences_datums)
 		load_path(parent.ckey)
 		if(load_and_save && !fexists(path))
 			try_savefile_type_migration()
-		unlock_content = !!parent.IsByondMember()
+
-		if(unlock_content)
+		refresh_membership()
-			max_save_slots = 8
 	else
 		CRASH("attempted to create a preferences datum without a client or mock!")
 	load_savefile()
@@ -536,3 +535,23 @@ GLOBAL_LIST_EMPTY(preferences_datums)
 			default_randomization[preference_key] = RANDOM_ENABLED
 
 	return default_randomization
+
+/datum/preferences/proc/refresh_membership()
+	var/byond_member = parent.IsByondMember()
+	if(isnull(byond_member)) // Connection failure, retry once
+		byond_member = parent.IsByondMember()
+		var/static/admins_warned = FALSE
+		if(!admins_warned)
+			admins_warned = TRUE
+			message_admins("BYOND membership lookup had a connection failure for a user. This is most likely an issue on the BYOND side but if this consistently happens you should bother your server operator to look into it.")
+		if(isnull(byond_member)) // Retrying didn't work, warn the user
+			log_game("BYOND membership lookup for [parent.ckey] failed due to a connection error.")
+		else
+			log_game("BYOND membership lookup for [parent.ckey] failed due to a connection error but succeeded after retry.")
+
+	if(isnull(byond_member))
+		to_chat(parent, span_warning("There's been a connection failure while trying to check the status of your BYOND membership. Reconnecting may fix the issue, or BYOND could be experiencing downtime."))
+
+	unlock_content = !!byond_member
+	if(unlock_content)
+		max_save_slots = 8