Kotlin's non-null type checks seemed nice, but I didn't start appreciating them until I had to debug a NPE being thrown 100 frames down a stack-trace in an enti

Kotlin's non-null type checks seemed nice, but I didn't start appreciating them until I had to debug a NPE being thrown 100 frames down a stack-trace in an entirely unsuspected piece of code in a legacy Java app.I had to release new debug code to production just to figure out where the hell it was happening. Just having the type system making 'this could be null' and 'this is assured to never be null' explicit would've saved me hours. Also, playing with Erlang made me really appreciate the actor model of concurrency.