fix: exit loop when paginated DB query returns empty array

fixes: https://github.com/mCaptcha/mCaptcha/issues/154

config/default.toml

@@ -34,11 +34,11 @@ enable_stats = true
 
 [captcha.default_difficulty_strategy]
 avg_traffic_difficulty =  50000 # almost instant solution
-#avg_traffic_time =  1 # almost instant solution
+avg_traffic_time =  1 # almost instant solution
 peak_sustainable_traffic_difficulty = 3000000 # roughly 1.5s
-#peak_sustainable_traffic_time = 3
+peak_sustainable_traffic_time = 3
 broke_my_site_traffic_difficulty = 5000000  # greater than 3.5s
-#broke_my_site_traffic_time = 5
+broke_my_site_traffic_time = 5
 duration = 30 # cooldown period in seconds
 
 [database]

src/easy.rs

@@ -55,6 +55,9 @@ impl UpdateEasyCaptcha {
             }
 
             let mut patterns = data.db.get_all_easy_captchas(limit, offset).await?;
+            if patterns.is_empty() {
+                break;
+            }
             for pattern in patterns.drain(0..) {
                 if !Self::can_run(rx) {
                     return Ok(());
@@ -85,6 +88,7 @@ impl UpdateEasyCaptcha {
             }
             page += 1;
         }
+        Ok(())
     }
 
     fn can_run(rx: &mut Receiver<()>) -> bool {