falling through blocks

Status
Invalid
Issue description

i recorded how it occurs to me and i don't know what to do. version 2020.2 (minecraft 1.12.2)

https://drive.google.com/open?id=1j_e1WQZx2jQK_lEFm3R9Wb8fLj2rsH1R

Issue comments

When possible, attach your MCreator workspace (or even better a minimal example workspace required to reproduce the bug), game logs (full logs, do not crop them, in text format, not screenshots of logs) from the Console tab or terminal and steps to reproduce the bug in your workspace. If logs are long, use service such as Pastebin to host the log and provide the link to the log from the ticket. Please specify which mod elements to check in your workspace too, if applicable.

Also, outdated version.

When possible, attach your MCreator workspace (or even better a minimal example workspace required to reproduce the bug)

Please specify which mod elements to check in your workspace too, if applicable.

it just crash the game, if I walk on these blocks in singleplayer, in multiplayer just exits the server