Source space map '' is not an image issue when running xcpengine

Having a bug when running xcpEngine on data from fmriprep, which I have specified in an open issue on the GitHub source code page: source space map '' is not an image issue when running xcpengine · Issue #444 · PennLINC/xcpEngine · GitHub

Perhaps this is already the best place for the bug to be reported, but I wanted to cross-post here in case anyone could help me with the issue.