If you hold RMB and then tap LMB while using the block, when you let go of both buttons, it will still give you the block path without the need to hold RMB. Sounds pretty harmless, but when you go past 50 blocks or the blocks that you have (idk which, i didnt do much testing) your client crashes.
Edit: upon testing, I found out that the amount of blocks that you have does not affect how far you go until the client crashes. I also found that you will stay logged into the server even though your client has ceased to work for a short amount of time. However i don't know if your sprite stays there or not or if this affects available server slots or not, but i do know that you cant join until the former you logs off, just wait a minute.