fix bug

app/views/exercises/_shixun_details.json.jbuilder

@@ -27,12 +27,17 @@ json.shixun_detail do
       json.output_detail output_detail game, output
     end
 
-    if game.try(:lastest_code).blank?
-      cha_path = challenge_path(shixun_challenge.challenge&.path)
-      latest_code = git_fle_content(shixun_challenge.shixun&.repo_path,cha_path)
+    if game.evaluate_count > 0
+      if game.try(:lastest_code).blank?
+        cha_path = challenge_path(shixun_challenge.challenge&.path)
+        latest_code = git_fle_content(shixun_challenge.shixun&.repo_path,cha_path)
+      else
+        latest_code = game.try(:lastest_code)
+      end
     else
-      latest_code = game.try(:lastest_code)
+      latest_code = nil
     end
+
     json.passed_code latest_code
   end
 end