temp fix crash due to race condition

we should fix the race condition though

Link: damus-io/nostrdb#35
Signed-off-by: William Casarin <[email protected]>

src/app.rs

@@ -379,26 +379,24 @@ fn poll_notes_for_timeline<'a>(
         debug!("{} new notes! {:?}", new_note_ids.len(), new_note_ids);
     }
 
-    let new_refs: Vec<(Note, NoteRef)> = new_note_ids
-        .iter()
-        .map(|key| {
-            let note = damus.ndb.get_note_by_key(txn, *key).expect("no note??");
-            let cached_note = damus
-                .note_cache_mut()
-                .cached_note_or_insert(*key, &note)
-                .clone();
-            let _ = get_unknown_note_ids(&damus.ndb, &cached_note, txn, &note, *key, ids);
-
-            let created_at = note.created_at();
-            (
-                note,
-                NoteRef {
-                    key: *key,
-                    created_at,
-                },
-            )
-        })
-        .collect();
+    let mut new_refs: Vec<(Note, NoteRef)> = Vec::with_capacity(new_note_ids.len());
+    for key in new_note_ids {
+        let note = if let Ok(note) = damus.ndb.get_note_by_key(txn, key) {
+            note
+        } else {
+            error!("hit race condition in poll_notes_into_view: https://github.com/damus-io/nostrdb/issues/35 note {:?} was not added to timeline", key);
+            continue;
+        };
+
+        let cached_note = damus
+            .note_cache_mut()
+            .cached_note_or_insert(key, &note)
+            .clone();
+        let _ = get_unknown_note_ids(&damus.ndb, &cached_note, txn, &note, key, ids);
+
+        let created_at = note.created_at();
+        new_refs.push((note, NoteRef { key, created_at }));
+    }
 
     // ViewFilter::NotesAndReplies
     {