fix: user popular project nil

app/views/user_rank/_detail.json.jbuilder

@@ -1,15 +1,19 @@
 owner_common = $redis_cache.hgetall("v2-owner-common:#{item[0]}")
 popular_project = $redis_cache.zrevrange("v2-user-project-rank:#{item[0]}", 0, 1, withscores: true)[0]
-popular_project_common = $redis_cache.hgetall("v2-project-common:#{popular_project[0]}")
 json.id item[0]
 json.score item[1]
 json.name owner_common["name"]
 json.type owner_common["type"]
 json.login owner_common["login"]
 json.avatar_url owner_common["avatar_url"]
-json.project do 
-  json.id popular_project[0]
-  json.name popular_project_common["name"]
-  json.identifier popular_project_common["identifier"]
-  json.description popular_project_common["description"]
+if popular_project.blank?
+  json.project nil
+else
+  popular_project_common = $redis_cache.hgetall("v2-project-common:#{popular_project[0]}")
+  json.project do 
+    json.id popular_project[0]
+    json.name popular_project_common["name"]
+    json.identifier popular_project_common["identifier"]
+    json.description popular_project_common["description"]
+  end
 end