When handcrafting the boiler, it will sometimes queue 4.2G stone furnaces and continue to make them for free. It will also do this with the filter inserter, queuing 4.2G fast inserters for free. It only does it sometimes so I'm not sure what the trigger is.

Hello BMGAradar!! Hmm.. i will see this now... Thanks for the info

I played with it a little bit and I can duplicate it by clicking shift and craft for "craft all". Hope that helps.

I can also duplicate the error when clicking to make fast underground belts, the normal underground belts go to 4.2G and canceling crashes the server