This update adds filtering similar to the one for written books and books and quills. This means that just like pages contained by written books are removed (they can't anyways be seen), items contained by Shulker Boxes won't be removed (shulker box contents are displayed as some sort of lore), but all additional item meta they might have will be stripped, leaving only the name untouched (that's the only thing you can see anyways). This should drastically reduce the amount of data sent to the client, making crashes impossible (unless the player uses tons of placeholders in the same message). I also recommend limiting the maximum amount of placeholders per message to no more then 8, as players can still abuse of filling a shulker box with items and then sending it 9 times in the same message, which is, by my calculations, enough to send the client just a bit more then the maximum allowed limit of 32767 bytes.