Previously this would only fail if *each* row had `:x:` in it, which was
never the case, because the header never has it. It is supposed to fail
when *at least one* row has an ❌.
Previously this would only fail if *each* row had `:x:` in it, which was
never the case, because the header never has it. It is supposed to fail
when *at least one* row has an ❌.