Join the Lockscreen Observer Beta Community to gain early access to new versions. New versions in beta status are not as stable as final versions and may contain failures that result in exceptions.
However, you also get the latest features to test. Your feedback in the community ist very welcome and helpfull for the further development.
If you want to switch back to the last official release, just leave the community and uninstall the beta version. You are know prepared to install the official release again in the App Store.