Exception handing in stats.xls and more debug info

app/controllers/conferences_controller.rb

@@ -436,7 +436,8 @@ class ConferencesController < ApplicationController
 		end
 
 		@registrations.each do |r|
-			if r.is_attending
+			if r && r.is_attending
+				begin
 					@total_registrations += 1
 					
 					@donation_count += 1 if r.registration_fees_paid
@@ -484,6 +485,10 @@ class ConferencesController < ApplicationController
 							:other => r.other || ''
 						}
 					end
+				rescue
+					logger.info "Error adding row to stats.xls"
+					logger.info "\t#{r ? r.to_yaml.to_s : 'nil'}"
+				end
 			end
 		end