Photon Melee 2 requires some special modifications in Melee 2 scripts, these modifications are made automatically after installing Photon Melee 2 but if you update Melee 2 these update will be overwritten.
To fix this follow these steps
Uninstall Photon Melee 2
Wait until script compilation finishes
Install Photon Melee 2
After this the errors should be gone, if you are still having troubles feel free to reach me at our Discord server