refactor: tweak loop a bit

Author: prestwich

src/tasks/env.rs

@@ -64,10 +64,9 @@ impl EnvTask {
             blocks.next().instrument(info_span!("EnvTask::task_fut::stream")).await
         {
             let Some(block) = blocks.last() else {
-                // Clear the env, as the block has changed but we can't
-                // get a new one
+                // This case occurs when there are no changes to the block,
+                // so we do nothing.
                 debug!("empty filter changes");
-                let _ = sender.send(None);
                 continue;
             };
             let span = info_span!("EnvTask::task_fut::loop", hash = %block, number = tracing::field::Empty);
@@ -84,13 +83,16 @@ impl EnvTask {
                     let _span = span.enter();
                     let _ = sender.send(None);
                     debug!("block not found");
+                    // This may mean the chain had a rollback, so the next poll
+                    // should find something.
                     continue;
                 }
                 Err(err) => {
                     let _span = span.enter();
                     let _ = sender.send(None);
                     error!(%err, "Failed to get latest block");
-                    break;
+                    // Error may be transient, so we should not break the loop.
+                    continue;
                 }
             };
             span.record("number", previous.number);