After removing a previous standalone modsuite in order to play Pyanodon's, I receive the following error when starting the game:
Failed to load mods: pypostprocessing/data-updates.lua:28: attempt to call global 'RECIPE' (a nil value)
Some analysis of the source for 0.2.3 indicates to me that you are attempting to use a function/class from Factorio Standard Library that does not exist or is deprecated. Is this the case?