@bac0npancakes: Confirmed this too. Nexon Launcher has successfully run MapleStory.
EDIT: This is what caused the extension.
[Update 7/14] We are looking into an issue with the Blaster Damage Skin and Summer Damage Skin, which causes players to crash. We have removed the Damage Skin Random Box from sale in the Cash Shop at this time.
[Resolved] The Blaster Damage Skin and Summer Damage Skin Coupons will no longer cause the game client to crash and will now be tradeable. If you already have either of these coupons prior to the log-in server maintenance, please restart the game client before using the coupons.
The Damage Skin Random Box is now back on sale for both Reboot and Non-Reboot worlds.