OTWO-7396 Fix missing method for project comparison (#1814)

Author: Priya5

app/controllers/compares_controller.rb

@@ -57,6 +57,8 @@ def setup_header
   end
 
   def metric_data(metric_name, project)
+    return [] unless metric_name
+
     data = project.best_analysis.send("#{metric_name}_history".to_sym, @start_date, @end_date)
     data.map do |values|
       metric_name == 'code_total' ? values['code_total'].to_i : values[metric_name.pluralize.to_s].to_i