There is a space between pri=0 and defaults. Spaces are field delimiters inside /etc/fstab, so there should be a comma instead of a space.
In addition to that, you’ve got too many options for your swap partition. This in itself won’t create the problem you’re seeing, but it’s futile as the swap partition does not contain a filesystem. Also, your discard option is wrong.
This below is the corrected line…
UUID=38e00dce-539e-4d9c-86ac-2f36a72579e0 swap swap pri=0,discard=pages 0 2