(diagnostic
  (schema slovo.diagnostic)
  (version 1)
  (severity error)
  (code TypeMismatch)
  (message "cannot call `std.vec.string.len` with argument of wrong type")
  (file "<fixture>")
  (span
    (bytes 57 58)
    (range 5 23 5 24)
  )
  (expected "(vec string)")
  (found "i32")
)