Merge pull request #2564 from whitequark/flatten-improve-error
authorwhitequark <whitequark@whitequark.org>
Fri, 29 Jan 2021 02:55:51 +0000 (02:55 +0000)
committerGitHub <noreply@github.com>
Fri, 29 Jan 2021 02:55:51 +0000 (02:55 +0000)
flatten: clarify confusing error message


Trivial merge