We should have some error handling

https://cloud.google.com/bigquery/docs/error-messages#errortable

If the cache expires and we can't fetch fresh data we should fall back
to a registry that is rebuilt via a nightly job.

app/services/popular_tasks/data_fetcher.rb

@@ -27,12 +27,19 @@ def sql_query(browse_page, raw_date)
       SQL
     end
 
-    def popular_task_data(page, date)
+    def fresh_popular_task_data(page, date)
       todays_popular_tasks_query = sql_query(page, date)
 
       Rails.cache.fetch("popular_tasks_for_#{page}", expires_in: 12.hours) do
         client.query(todays_popular_tasks_query).all
       end
+    rescue SomeBigQueryErrorCodes
+      to_be_implemented_report_error
+      []
+    end
+
+    def popular_task_data(page, date)
+      fresh_popular_task_data(page, date) || to_be_implemented_popular_tasks_registry(page)
     end
   end
 end