编译错误时 计算系统评分不正确

app/models/student_work_test.rb

@@ -45,7 +45,7 @@ class StudentWorkTest < ActiveRecord::Base
   private
   def get_success_count
     self.results.inject(0) do |sum, result|
-      sum += (result["status"].to_i == 0 ? 1 : 0)
+      sum += (result["status"] && result["status"].to_i == 0 ? 1 : 0)
     end || 0
   end