This function, gollorum.signpost.blocks.SuperPostPost.getSuperTile(SuperPostPost.java:245), just keeps calling itself forever causing a stack overflow.

latest.log
crash-2019-03-28_03.58.31-server.txt

Here's the problem line:

Changing this line from tile = getSuperTile(pos); to tile = pos.getTile(); should fix it.

Not sure what you're trying to do on line 244...

Fixed with version 1.08.1
I too am unsure what that line is supposed to do, but I am afraid something will break if I remove it. I think it had something to do with getTile() returning null if the chunk at that position was not loaded and me having no idea what I'm doing.
Anyway, thank you for pointing out this issue :D