fixed 项目排行导出增加3列,时间处理

app/controllers/admins/projects_rank_controller.rb

@@ -43,7 +43,7 @@ class Admins::ProjectsRankController < Admins::BaseController
       sheet[index+1,1] = "#{d&.project&.owner&.real_name}/#{d&.project&.name}"
       sheet[index+1,2] = "#{Rails.application.config_for(:configuration)['platform_url']}/#{d&.project&.owner&.login}/#{d&.project&.identifier}"
       sheet[index+1,3] = d&.project&.project_category&.name
-      sheet[index+1,4] = d&.project&.created_on.to_s.strftime("%Y-%m-%d %H:%M:%S")
+      sheet[index+1,4] = d&.project&.created_on.present? ? d&.project&.created_on.strftime("%Y-%m-%d %H:%M:%S") : ""
       sheet[index+1,5] = d&.project&.common? ? "独立创建" : "外部迁移"
       sheet[index+1,6] = d.score
       sheet[index+1,7] = d.visits