Fix: semaphore rate limiting, integer underflow, unreachable panics, silent error swallowing, division by zero

Author: buzzkillb

src/bot.rs

@@ -209,7 +209,9 @@ impl Bot {
         match self.database.get_price_history(crypto_name, 30) {
             Ok(history) => {
                 if history.is_empty() {
-                    let _ = channel_id.say(&ctx.http, "❌ No historical data available yet (waiting for data to be collected)").await;
+                    if let Err(e) = channel_id.say(&ctx.http, "❌ No historical data available yet (waiting for data to be collected)").await {
+                        warn!("Failed to send empty history message: {}", e);
+                    }
                     return Ok(());
                 }
                 match generate_price_chart(&history, crypto_name) {
@@ -305,8 +307,10 @@ impl Bot {
                 .or_else(|| all_prices.get("PAXG"));
 
             if let Some(gold) = gold_price {
-                let ratio = gold / current_price;
-                conversion_prices.push(format!("Ratio: {:.2} (Au/Ag)", ratio));
+                if current_price > 0.0 {
+                    let ratio = gold / current_price;
+                    conversion_prices.push(format!("Ratio: {:.2} (Au/Ag)", ratio));
+                }
             }
         }
 
@@ -722,7 +726,9 @@ impl EventHandler for Bot {
             lines.push("```".to_string());
 
             let message = lines.join("\n");
-            let _ = msg.channel_id.say(&ctx.http, message).await;
+            if let Err(e) = msg.channel_id.say(&ctx.http, message).await {
+                warn!("Failed to send health status message: {}", e);
+            }
             self.health.update_discord_timestamp();
         } else {
             debug!(
@@ -775,7 +781,10 @@ async fn read_prices_from_file() -> BotResult<PricesFile> {
         }
     }
 
-    unreachable!()
+    Err(BotError::Io(std::io::Error::new(
+        std::io::ErrorKind::Other,
+        "Unexpected error in prices file read retry loop",
+    )))
 }
 
 /// Main price update loop with comprehensive error handling
@@ -1125,7 +1134,11 @@ fn format_custom_status(
                 .map(|p| p.price);
 
             let ratio_str = if let Some(gold) = gold_price {
-                format!("Au/Ag: {:.2}", gold / current_price)
+                if current_price > 0.0 {
+                    format!("Au/Ag: {:.2}", gold / current_price)
+                } else {
+                    format!("{:.8} ₿", btc_amount)
+                }
             } else {
                 format!("{:.8} ₿", btc_amount) // Fallback
             };
@@ -1395,7 +1408,10 @@ async fn get_individual_crypto_price(feed_id: &str) -> BotResult<f64> {
         }
     }
 
-    unreachable!()
+    Err(BotError::Io(std::io::Error::new(
+        std::io::ErrorKind::Other,
+        "Unexpected error in prices file read retry loop",
+    )))
 }
 
 /// Test Discord connectivity by making a simple API call

src/database.rs

@@ -163,7 +163,16 @@ impl PriceDatabase {
         ];
 
         for (seconds, label) in periods {
-            let time_ago = current_time - seconds;
+            // Guard against underflow if clock goes backwards
+            let time_ago = if current_time >= seconds {
+                current_time - seconds
+            } else {
+                debug!(
+                    "Clock appears to have gone backwards, skipping {} price lookup",
+                    label
+                );
+                continue;
+            };
 
             // Try to get price from appropriate data source based on age
             let old_price = if seconds <= 24 * 3600 {

src/discord_api.rs

@@ -27,12 +27,13 @@ impl DiscordApi {
     }
 
     /// Rate-limited Discord API call helper
+    #[allow(unused_variables)]
     async fn rate_limited_call<F, Fut, T>(&self, mut operation: F) -> Result<T, serenity::Error>
     where
         F: FnMut() -> Fut,
         Fut: std::future::Future<Output = Result<T, serenity::Error>>,
     {
-        let _permit = self
+        let permit = self
             .semaphore
             .acquire()
             .await
@@ -41,7 +42,7 @@ impl DiscordApi {
         // Enforce minimum delay between calls
         sleep(Duration::from_millis(RATE_LIMIT_DELAY_MS)).await;
 
-        // Execute the operation with retry logic
+        // Execute the operation with retry logic - permit is held during all attempts
         for attempt in 1..=MAX_RETRIES {
             match operation().await {
                 Ok(result) => return Ok(result),
@@ -63,7 +64,7 @@ impl DiscordApi {
             }
         }
 
-        unreachable!()
+        Err(serenity::Error::Other("Rate limiting exhausted"))
     }
 
     /// Update bot nickname in a specific guild

src/price_service.rs

@@ -146,7 +146,7 @@ async fn get_crypto_price(feed_id: &str) -> Result<f64, Box<dyn std::error::Erro
         }
     }
 
-    unreachable!()
+    Err("Unexpected error in price fetch retry loop".into())
 }
 
 pub async fn fetch_shanghai_history(