minor cleanup

I checked out some of the codeclimate "smells" and made some fixups.

In general, checking ```if !thing.nil?``` is equivalent to checking ```if thing```, and checking ```if  !thing.nil?``` before calling a method on it isn't correct -- you want to check ```thing.is_a?(Klass)``` where ```Klass``` implements the method, or check for the method directly with ```thing.responds_to?(:method)```.


Thanks for maintaining this project!
Please let me know if you have any questions or comments.