Minimal reproduction of errors when loadings Remix v1.8+ apps in Vercel Preview environments with their new Comments feature enabled.
The injected scripts for this feature make an OPTIONS request to / on startup, which triggers a 405 response (more details on original issue). The script appears to fail gracefully, so this is not completely breaking, but may have knock on effects for other apps.
This is a bare minimum reproduction of what the Vercel script is doing on startup. The error was originally noticed on a Remix v1.8.2 app, but this reproduction shows the error happening in the latest v1.10.0 of Remix too.
Install deps with your package manager of choice, run the dev or prod builds and navigate to http://localhost:3000. You should see the server error in the terminal, and the 405 response in your browsers Network tab.