I added a new screen shot. It happened again on a single player world on vanilla Minecraft 1.16.3, no mods.
I provided a picture of it. (this is in vanilla Minecraft on a different pc then I originally reported the bug, and it still happened.
To add to this, custom data packs are not required. To repro you can simply disable the vanilla datapack.
Here's my game output: https://pastebin.com/Swp0ihdt
Here's the actual crash report: https://pastebin.com/ESKYnTxA
confirmed in 18w03b
Actually, upon further investigation, I think this is working as intended.
Thanks, sorry for the report!
Hmm, odd. Yes setting it to HurtTime:9s does work!