Failed to load participants info due to: 'float' object has no attribute 'lower'

[yarikoptic]

might be a non-issue - just want to record before I forget

[INFO   ] Aggregate metadata for dataset /mnt/btrfs/datasets-meta6-6/datalad/crawl/openfmri/ds000017
Metadata extraction: 100%|████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████| 5.00/5.00 [01:29<00:00, 24.5s/ extractors][WARNING] Failed to load participants info due to: 'float' object has no attribute 'lower' [bids.py:yield_participant_info:202]. Skipping the rest of file    

whenever file seems to be kosher

$> cat /mnt/btrfs/datasets-meta6-6/datalad/crawl/openfmri/ds000017/participants.tsv
participant_id  sex     age
sub-1   n/a     n/a
sub-2   M       44
sub-3   n/a     n/a
sub-4   M       49
sub-5   F       49
sub-6   M       25
sub-7   n/a     n/a
sub-8   M       50