Here’s a list of Issues that need to be addressed prior to the 5.0.1 release (the list is large, but it’s really not that bad ):
5.0.1 Milestone · GitHub
Note I just did broad superficial testing of OpenEMR (especially php 7.1 testing) and placed the issues that I noted in list linked above.
Regarding the list of issues, basically, the more red you see per Issue, the more serious it is.
Please, please, please, feel free to pick up Issues and fix them. The PHP bug fixes are perfect small and quick fixes to learn more about OpenEMR codebase and development.