Create custom exception

lib/uk_planning_scraper.rb

@@ -5,4 +5,6 @@ require 'uk_planning_scraper/northgate'
 require 'logger'
 
 module UKPlanningScraper
+  class SystemNotSupportedError < StandardError
+  end
 end

lib/uk_planning_scraper/authority.rb

@@ -45,7 +45,7 @@ module UKPlanningScraper
         apps = self.scrape_northgate(authority.url, params, options)
       else
         # Not supported
-        raise "Planning system not supported for #{@name} at URL: #{@url}"
+        raise SystemNotSupportedError.new("Planning system not supported for #{@name} at URL: #{@url}")
       end
       
       # Post processing