When depexts are missing and the combine length of the names of all depexs is sufficiently short, there is no newline between the error message and the list of depexts

[gridbugs]

To reproduce, set up a project depending on a package with depexts and mess with that package's lockfile so it doesn't build. Dune will give a hint that the failure might be depext-related and print:

Hint: You may want to verify the following depexts are installed:
- depext1
- depext2

However if the combined length of depext names is too short it prints this instead:

Hint: You may want to verify the following depexts are installed:- a
                                                                 - b