During peer-review, should I comment on the authors' messy code? I'm reviewing a paper in pure mathematics. A lot of results in the paper depend heavily on computer computations, and the authors have provided in the article a link to the Magma code they used for most of these computations. However, this code is almost impossible to understand due to the messy way it is written. For example, it does not use any indentation, and all variables are given names like 'aaa' or 'X' that do not give any information about their purpose in the program. 

On the one hand, the mathematics underlying these computations is explained sufficiently well that it is possible to reproduce the results without using the authors' code (this is what I ended up doing). Also, the paper contains only a link to the code and not the actual code itself, so I'm not sure if the code is really in scope for the review. Moreover, hard-to-read code seems to not be uncommon in academia, and most people don't seem to mind. On the other hand, I think a small amount of work from the authors (who presumably do understand the code) would make this code a lot more usable for others, just by replacing some of the variable names with names that actually convey some meaning. 

My question is, is it reasonable for me to tell the authors that their code is needlessly difficult to understand and should be improved?
If the authors have provided a link to their code as a reference, then it is appropriate to offer commentary, particularly if the article is based on the code.

However, I would recommend making the critique constructive: offer concrete suggestions for how to improve it rather than just saying it’s “messy” or “sloppy” and needs to be “cleaned up.”