0.9.23 tries to catch files that might crash the game early. A few bad HWPs have been floating around that could cause this.

• Any that have an old version of the Beach theme - beach is now an official theme and they are likely to mismatch.

• Hedgecraft - unfortunately the Hedgecraft HWP was badly packaged and overrides rubber globally, instead of just in the mod.

Any lua script that modifies key images that could change the map like girder, rubber or theme objects needs to be packaged like this:
MAIN.HWP → script.lua, script.hwp

With the override graphics of the script.hwp kept safely tucked away.

That way script.hwp will only be loaded when script.lua is launched.