feat: don't panic if `Db::compact_chunks` with no matching chunks (#2818)

server/src/db.rs

@@ -659,12 +659,16 @@ impl Db {
             // Get a list of all the chunks to compact
             let chunks = LockablePartition::chunks(&partition);
             let partition = partition.upgrade();
-            let chunks = chunks
+            let chunks: Vec<_> = chunks
                 .iter()
                 .map(|chunk| chunk.write())
                 .filter(|chunk| predicate(&*chunk))
                 .collect();
 
+            if chunks.is_empty() {
+                return Ok(None);
+            }
+
             let (_, fut) = lifecycle::compact_chunks(partition, chunks).context(LifecycleError)?;
             fut
         };