How to handle case where no RNA families are found

[amorehead]

Hi, @fdimaio. Thanks again for making this project open-source. I had a question RNA MSA generation. For some small RNA sequence inputs I've tried running through RF2NA, the RNA MSA generation script (i.e., make_rna_msa.sh) issues a series of errors stemming from the following line, in the event that no RNA families are found by cmscan. It seems like in this case all proceeding lines fail because they assume at least one family was found. Is there a simple adjustment that we can make to this MSA generation script to handle the case where no RNA families are found? For example, would this simply mean that the script should exit early instead of proceeding with subsequent steps?

Another way of phrasing this questions would be, does RF2NA have a way of performing single-sequence predictions for RNA FASTA inputs? If not, what changes would likely be necessary?

https://github.com/uw-ipd/RoseTTAFold2NA/blob/03f12bd421db618455d9c0726f79f72433a8638e/input_prep/make_rna_msa.sh#L62C1-L62C1

[amorehead]

For anyone else who is interested in making single-sequence RNA structure predictions with RF2NA, feel free to have a look at my open PR that "should" address one of the basic MSA construction issues that arises in this scenario.