In any case you see this error while using Events Maker the reason is probably the same. It points to get_current_screen() function called too early in WP loading process.
There must be a different plugin or piece of code in your themes calling that function in a hook in which it is not yet available. The code in Events Maker just exposes the bad coding practice (or just a mistake) a developer made elsewhere.
I know it sounds weird but I can assure you, that’s how it is :)