fixes #2385

app/controllers/sources_controller.rb

@@ -12,4 +12,14 @@ class SourcesController < ApplicationController
       end
     end
   end
+
+private
+
+  def rescue_exception(exception)
+    respond_with do |format|
+      format.json do
+        render :json => {:message => exception.to_s}, :status => :error
+      end
+    end
+  end
 end