Thanks for your report, @MikkelFeilberg.
UPDATE: This can now be solved by updating to Local 9.2.8 or higher.
Old steps, no longer needed but retained for context
Please can you try running the following commands from your terminal to install mailpit? For others reading, these steps apply to Intel Macs on 9.2.7 only and only if you’re seeing the same issue.
First, make sure you’re running 9.2.7. Then quit Local. Open a Terminal and run these one at a time:
cd ~/Library/Application\ Support/Local/lightning-services
curl -O https://cdn.localwp.com/site-services-lightning/mailpit/support-fix/mailpit-1.24.1+0.zip
unzip mailpit-1.24.1+0.zip
rm mailpit-1.24.1+0.zip
Then start Local. Your “Missing Mailpit” error should be cleared.