Mgd77list with missing fields

To extract data from an mgd77 file, the short-hands mgd77, geo, etc. return a table with NaN columns for missing fields. But if I specify a custom list of fields, the program fails to return a table if one of them is missing. I could not find an option to tell the program to succeed even if a field is missing. Is there a mean to achieve this?
Thank you for reading.

Edit: I have just realized that it happens when I request an auxiliary field (namely az) that is not in the data. This is perhaps perfectly normal, not sure.

Edit2: My mistake, mgd77list always fail if a field if missing, even with the short-hands (I tried mgd77t on a file without the bqc field). So I think it is rather a feature request: that mgd77list be always successful, with NaN columns for missing fields…

I think this is a good idea so that for folks who script or program actions can always count on a similar return even if some columns are entirely NaNs. Please open a feature request on GitHub.