check if method exists for scene

upate Gemfile

examples/obs/Gemfile

@@ -2,4 +2,4 @@
 
 source "https://rubygems.org"
 
-gem "obsws", "~> 0.1.3"
+gem "obsws", "~> 0.3.0"

examples/obs/main.rb

@@ -44,8 +44,10 @@ class Main
   def on_current_program_scene_changed(data)
     scene = data.scene_name
     puts "Switched to scene #{scene}"
+    if respond_to?("on_#{scene.downcase}")
       send("on_#{scene.downcase}")
     end
+  end
 
   def on_exit_started
     puts "OBS closing!"