Harden stream queues and hostile network tests

src/bin/dosh-client.rs

@@ -6253,7 +6253,9 @@ async fn flush_stream_pending_data(
         if credit < bytes.len() {
             break;
         }
-        let bytes = pending.pop_front().expect("pending front exists");
+        let Some(bytes) = pending.pop_front() else {
+            break;
+        };
         *stream_send_credit.entry(stream_id).or_default() -= bytes.len();
         let offset = *stream_next_send_offset.entry(stream_id).or_default();
         stream_next_send_offset.insert(stream_id, offset.saturating_add(bytes.len() as u64));

src/bin/dosh-server.rs

@@ -2752,10 +2752,13 @@ async fn handle_file_request(
                 atomic,
             });
             if let Some(mode) = mode {
-                let target = upload
+                let Some(active_upload) = upload.as_ref() else {
+                    return Err(anyhow!("upload state missing after start"));
+                };
+                let target = active_upload
+                    .temp_path
                     .as_ref()
-                    .and_then(|state| state.temp_path.as_ref())
-                    .unwrap_or_else(|| &upload.as_ref().unwrap().final_path)
+                    .unwrap_or(&active_upload.final_path)
                     .clone();
                 set_mode(&target, mode)?;
             }
@@ -3243,7 +3246,10 @@ async fn flush_stream_pending_data_to_client(
                 if credit < bytes.len() {
                     return Ok(());
                 }
-                let bytes = pending.pop_front().expect("pending front exists");
+                let Some(bytes) = pending.pop_front() else {
+                    client.stream_pending_data.remove(&stream_id);
+                    return Ok(());
+                };
                 if pending.is_empty() {
                     client.stream_pending_data.remove(&stream_id);
                 }

src/transport.rs

@@ -596,11 +596,13 @@ impl StreamMux {
             if self.send_credit.get(&stream_id).copied().unwrap_or(0) < front_len {
                 break;
             }
-            let bytes = self
+            let Some(bytes) = self
                 .pending_data
                 .get_mut(&stream_id)
                 .and_then(VecDeque::pop_front)
-                .expect("pending front exists");
+            else {
+                break;
+            };
             if self
                 .pending_data
                 .get(&stream_id)