I know pandoc has many different versions, I am running pandoc 126.96.36.199.
hashing program used: xxhsum
Processing files in site: bunnies
Site-wide changes detected in 'www/bunnies'. Cleaning now.
Cleaning generated files from site: 'bunnies'
pandoc: Unknown extension: smart
Updating to the most modern version of pandoc seems to fix the issue.