fix: 提出ページが404のコンテストは即スキップしてクロールを高速化する

atcoder-problems-backend/crawler/src/client.rs

@@ -125,6 +125,9 @@ impl CrawlerClient {
         );
         let request = self.client.get(&url);
         let response = request.send().await?;
+        if response.status() == 404 {
+            return Err(CrawlerError::NotFound);
+        }
         if !response.status().is_success() {
             return Err(CrawlerError::HttpError(response.text().await?));
         }

atcoder-problems-backend/src/crawler_utils.rs

@@ -23,6 +23,14 @@ pub async fn fetch_submissions(
             Ok(submissions) => {
                 return submissions;
             }
+            Err(CrawlerError::NotFound) => {
+                tracing::warn!(
+                    "Submissions page not found for contest {} page {} (404), skipping",
+                    contest_id,
+                    page
+                );
+                return vec![];
+            }
             Err(e) => {
                 retry_count += 1;
                 tracing::warn!(