Write errors to an SSD usually means it dropped offline, but without the syslog can never say for sure.
Scrub only checks the data, it doesn't check files system consistency, you can leave it as is for now and see if it doesn't happen again, just make sure backups are current.
You can also run btrfs check --readonly, but if errors are detected best to format instead of trying to fix them, btrfs fsck is still very fragile, and can even make things worse when trying to fix a corrupt file system.