require("CCS811").connectI2C(i2c);

Just gas.get() should print out the result on the console.

@Gordon just checked, gas.get(print) does work. But (was puzzled about the "why does it work at all?") that snippet is "wrong". It's working as intended, but the print is not needed / used by the code. The REPL just prints out the result. Or is there some magic in the background?