A couple of months ago, I created a Sentry integration for Nextcloud. Back then, I focussed on integrating the PHP SDK to automatically report all logged PHP exceptions to a Sentry instance.
Right now, the Sentry client does its magic in detecting those exceptions. The APIs to manually report errors are not yet exposed.
The app is available via the app store. If you have already used the previous version, Nextcloud will soon ask you to update to 2.0.0.
The configuration requires a small change, so please take a look at the admin docs after the update.
If you have any questions, discovered a bug or want to request a new feature, feel free to create a ticket on GitHub.