fix: prevent empty indexes when using --reindex always

When reindexing, the indexes are "reset", which basically means that
new indexes are being created. However, the loop still holds on to the
old writers. So when resetting the indexes, we must also create new
writers.

Otherwise the logic will write to the old indexes, and the new ones
will stay empty.

indexer/src/lib.rs

@@ -216,10 +216,18 @@ where
     async fn handle_reindex(&mut self, writers: &mut Vec<IndexWriter>) -> anyhow::Result<()> {
         log::info!("Reindexing all documents");
 
+        // set the indexes
         for index in &mut self.indexes {
             index.reset()?;
         }
 
+        // after resetting, we need to acquire new writers, as the old indexes are gone
+        writers.clear();
+        for index in self.indexes.iter_mut() {
+            writers.push(block_in_place(|| index.writer())?);
+        }
+
+        // now walk the full content with the new (empty) indexes
         const MAX_RETRIES: usize = 3;
         let mut retries = MAX_RETRIES;
         let mut token = ContinuationToken::default();