If the matched jet energy is 0 then the smearing function outputs nonsense numbers (it uses the difference between the reconstructed jet and the generated jet pts). I'm not sure how often it happens but there are definitely some jets which have generated jet energy = 0 because that is why we decided to introduce this requirement initially.

I have just noticed that they have updated the factors for jet smearing and slightly modified the code in the twiki, so I will make an issue for that and make sure it is done before we next run the Analysis Tools.