On the newest version released this morning, whenever the knocker appears outside at the same time as the player (The same event where it gives the player slowness) It crashed the game to the launcher when it vanishes. The crash report for this event is as follows
"The game crashed whilst exception in server tick loop
Error: java.lang.NullPointerException: Cannot read field "f_19853_" because the return value of "java.util.Optional.orElse(Object)" is null"

can you send the crash log?