fix(esplora): error if keychain iteration yields no indices

Author: reez

crates/esplora/src/async_ext.rs

@@ -348,6 +348,9 @@ where
             .collect::<FuturesOrdered<_>>();
 
         if handles.is_empty() {
+            if last_index.is_none() {
+                return Err(Box::new(esplora_client::Error::InvalidResponse));
+            }
             break;
         }
 
@@ -368,7 +371,8 @@ where
                 .extend(evicted.into_iter().map(|txid| (txid, start_time)));
         }
 
-        let last_index = last_index.expect("Must be set since handles wasn't empty.");
+        let last_index =
+            last_index.ok_or_else(|| Box::new(esplora_client::Error::InvalidResponse))?;
         let gap_limit_reached = if let Some(i) = last_active_index {
             last_index >= i.saturating_add(stop_gap as u32)
         } else {
@@ -571,6 +575,15 @@ mod test {
         }};
     }
 
+    #[test]
+    fn ensure_last_index_none_returns_error() {
+        let last_index: Option<u32> = None;
+        let err = last_index
+            .ok_or_else(|| Box::new(esplora_client::Error::InvalidResponse))
+            .unwrap_err();
+        assert!(matches!(*err, esplora_client::Error::InvalidResponse));
+    }
+
     // Test that `chain_update` fails due to wrong network.
     #[tokio::test]
     async fn test_chain_update_wrong_network_error() -> anyhow::Result<()> {

crates/esplora/src/blocking_ext.rs

@@ -343,7 +343,8 @@ fn fetch_txs_with_keychain_spks<I: Iterator<Item = Indexed<SpkWithExpectedTxids>
                 .extend(evicted.into_iter().map(|txid| (txid, start_time)));
         }
 
-        let last_index = last_index.expect("Must be set since handles wasn't empty.");
+        let last_index =
+            last_index.ok_or_else(|| Box::new(esplora_client::Error::InvalidResponse))?;
         let gap_limit_reached = if let Some(i) = last_active_index {
             last_index >= i.saturating_add(stop_gap as u32)
         } else {
@@ -561,6 +562,15 @@ mod test {
         ));
     }
 
+    #[test]
+    fn ensure_last_index_none_returns_error() {
+        let last_index: Option<u32> = None;
+        let err = last_index
+            .ok_or_else(|| Box::new(esplora_client::Error::InvalidResponse))
+            .unwrap_err();
+        assert!(matches!(*err, esplora_client::Error::InvalidResponse));
+    }
+
     macro_rules! local_chain {
         [ $(($height:expr, $block_hash:expr)), * ] => {{
             #[allow(unused_mut)]