In the latest version of this mod for 1.16.5 (as of 2021-12-11) pressing Escape in the signpost UI causes the client to crash to desktop.
Here's the error message:

The game crashed whilst keypressed event handler
Error: java.lang.NullPointerException: keyPressed event handler
Exit Code: -1

Hey, sorry for the delay.
In order for me to reproduce this, I'd appreciate if you could give me some more details:

• Does this happen every time or just in some circumstances?
• What other mods are installed?

Probably fixed with version 2.00.4, plz reopen if it still happens