more rubocop fixes

Author: monkstone

lib/jruby_art/runner.rb

@@ -200,9 +200,9 @@ def spin_up(starter_script, filename, argc)
 
     # NB: We really do mean to use 'and' not '&&' for flow control purposes
     def ensure_exists(filename)
-      unless FileTest.exist?(filename)
-        puts("Couldn't find: #{filename}") and exit
-      end
+      return if FileTest.exist?(filename)
+
+      puts("Couldn't find: #{filename}") and exit
     end
 
     def jruby_complete

library/vector_utils/vector_utils.rb

@@ -49,7 +49,7 @@ def self.spiral_layout(number:, radius:, resolution:, spacing:, inc:)
 
   def self.cartesian_to_polar(vec:)
     res = Vec3D.new(vec.mag, 0, 0)
-    return Vec3D.new unless res.x > 0
+    return Vec3D.new unless res.x.positive?
 
     res.y = -Math.atan2(vec.z, vec.x)
     res.z = Math.asin(vec.y / res.x)