I'm trying to play with this mod and scrappy chemistry, but when I load the two together I get the error below.
I checked the configs, this happens on both standard and remix configs w/ scrappy chemistry. When I checked the config for this mod I didn't see anything that seemed related to syn gas -> petroleum gas.

This log is from scrappy chemistry and basic chemistry alone and with default configs.

Failed to load mods: basic-chemistry/prototypes/compat/scrap-chemistry.lua:10: attempt to index field 'bc-petroleum-gas-from-syn-gas' (a nil value)
stack traceback:
basic-chemistry/prototypes/compat/scrap-chemistry.lua:10: in main chunk
[C]: in function 'require'
basic-chemistry/data.lua:28: in main chunk

Thanks for the report!

Well, I somewhat forgot about my attempt at the scrappy chemistry compat I made a while ago …
Scrappy chemistry has changed quite a bit since I made these and so I've removed most of the compat.
I've uploaded a fix with just the bare minimum compat for scrappy chemistry (i.e. basic chemistry uses the methane resource provided by scrappy chemistry instead of its own.)

I'd like to do a proper compat with scrappy chemistry at some point but I currently don't have the capacity for it.