• This issue is not solved in a development build
  I am on version 5.3.0-SNAPSHOT-723 of the protocol lib jar and 5.1.0 of the api

Describe the bug
A clear and concise description of what the bug is.
When sending a PacketType.Play.Server.ENTITY_METADATA the server kicks all online players and sends them the error below.

To Reproduce
Steps to reproduce the behavior:
pastebin of the code here > https://pastebin.com/6abPScvd
Error log: https://pastebin.com/fFNBYiLA

Expected behavior
A clear and concise description of what you expected to happen.
It doesn't kick players

Screenshots
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https://imgur.com/a/glTqs1I

Version Info
Provide your ProtocolLib install info with /protocol dump through pastebin.
https://pastebin.com/32UUfRmR

Additional context
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