-- Fix bug where Homer3 does not find any SNIRF data files when reloading the same dataset that was already processed for the first time. Problem occurred only when a non-loadable, non-data file probe.snirf is present in the root dataset folder.
(To reproduce this issue, comment out the one-line fix and add ONE non-data SNIRF file (such as probe.snirf, which will not be loaded) while the actual data files are in subject folders. Load first time in Homer in a clean group folder that has no derivatives folder. Then exit, restart Homer and the second time it will not find ANY data files asking you find a group data folder with snirf files in it.)