Run test on sets with some lacking files

Hi all,
I am currently trying to run a method where I basically merge 300 files (.bai files for examples) from all my samples.

I get that error message:
2018/03/25 17:14:20 E: command failed: CommandException: No URLs matched: gs://XXXX
CommandException: 1 file/object could not be transferred.

My method fails because some .bai of some samples are not created yet.

Is there a way to merge the existing files anyway, without taking into account the .bai files that don't exit yet?

Thank you,
CDG