Very minor grammar fix in error message
minor #13036 [Config] Very minor grammar fix in error message (WouterJ)

This PR was merged into the 2.3 branch.

Discussion
----------

[Config] Very minor grammar fix in error message

It's just a tiny detail, but I found it important enough to submit a fix.

| Q   | A
| --- | ---
| License | MIT
| Fixed tickets | -

Commits
-------

1c65f36 Very minor grammar fix in error message