Go to the shop and purchase the clear inventory, and telport back to spawn if needed for free, and you should be fine. http://shop.mineverse.com/
That screenshot doesn't prove it's RPHanson's. Nevertheless, you can get a free inven clear on the shop. I believe that the glitch chest, if it came from a client which is free, might be either from Impact or Wurst.
Lol I mean I was pretty sure it was PlayerESP but I wasn't going to call him out and report back then because I was pretty meh... XD But rekt tho
Yeah I once got a crash chest on a server before and this is how I fixed it (note: this server didn't have a clear inventory buycraft option) So since you're having troubles with buycraft, I recommend you going on Minechat (an app that you can download on the app/play on your phone) logging in with your minecraft account, adding Mineverse, and typing in /creative to go into creative. It should not disconnect you so you can just do /ci and your inventory will be cleared. If this doesnt work then idk ~