Backends send helpful information on composite key errors but we don't get to see it.

-Before submitting your PR, check that you've:

• [x ] Ran stylish-haskell on any changed files.
• [ x] Adhered to the code style (see the .editorconfig file for details)

After submitting your PR:

• [ x] Update the Changelog.md file with a link to your PR
• [ x] Bumped the version number if there isn't an (unreleased) on the Changelog
• [ x] Check that CI passes (or if it fails, for reasons unrelated to your change, like CI timeouts)