[TothBenoit]

createDirectory creates each missing part of the path in turn, checking exists(part) and then calling sys_create_dir. If another process creates that same directory between the check and the create, sys_create_dir fails and the function throws. The directory does exist at that point, and the levels below it are never created.

This happens when several processes create overlapping directory trees at the same time, for example parallel asset converters writing under a shared output folder.

The fix: when sys_create_dir fails, check exists(part) again and throw only if the directory still isn't there, the same as mkdir -p.