(diagnostic
  (schema slovo.diagnostic)
  (version 1)
  (severity error)
  (code UnsupportedMatchMutation)
  (message "match subject cannot be an option/result assignment")
  (file "<fixture>")
  (span
    (bytes 69 74)
    (range 5 15 5 20)
  )
  (hint "evaluate and match an immutable option/result value")
)