show error message on chart if channel not found

app/controllers/feed_controller.rb

@@ -5,7 +5,7 @@ class FeedController < ApplicationController
 
   def index
     feed_factory = FeedFactory.new(params)
-    channel = Channel.find(params[:channel_id])
+    channel = feed_factory.channel
     api_key = ApiKey.find_by_api_key(get_apikey)
     @success = channel_permission?(channel, api_key)
 

app/models/feed_factory.rb

@@ -18,7 +18,7 @@ class FeedFactory < ApplicationController
   end
 
   # attributes that can be read
-  attr_reader :feeds, :daily_feeds, :limit, :use_daily_feed, :feed_select_options, :cache_feeds
+  attr_reader :feeds, :daily_feeds, :limit, :use_daily_feed, :feed_select_options, :cache_feeds, :channel
 
   # calculate the limit that should be used
   def calculate_limit

app/views/charts/show.html.erb

@@ -185,7 +185,12 @@
             // draw the chart
             var dynamicChart = new Highcharts.Chart(chartOptions);
 
-        }); // end getJSON ajax call
+        // end getJSON success
+        })
+        // chained to getjson, on error
+        .error(function() {
+          $('#chart-container').html('Invalid Channel.');
+        });
 
       }); // end document.ready