Please provide the crash-log. It has all the answers.
Your eventhandler also looks awefully a lot like a TextComponentString class, not an actual class that deals with events...
For now I'm going to guess that you're using the PlayerLoggedInEvent?
You need to wait a tick before doing anything with the given player from that event; it isn't fully initialized, leading to several null-pointers.
As I discovered in this topic, you need to set Block#useNeighborBrightness to true. For some reason, Vanilla does this in Block.registerBlocks instead of in the constructors of the appropriate Block classes.