Can't measure date intervals in large units

[mtoy-googly-moogly]

run: duckdb.sql("SELECT DATE '2001-01-01' AS dstart, DATE '2002-02-01' AS dend") -> {
  select: dstart, dend, ddiff is months(dstart to dend)
}

Errors with Cannot measure interval using 'month'

According to https://docs.malloydata.dev/documentation/language/time-ranges#interval-measurement it should work.