added the fix for snetence encoder

app.py

@@ -205,7 +205,7 @@ if len(ALL_FILES) > 0:
             # extract batch
             batch = [doc.content for doc in docs[i:i_end]]
             # generate embeddings for batch
-            emb = retriever.encode(batch).tolist()
+            emb = sentence_encoder.encode(batch).tolist()
             # get metadata
             meta = [doc.meta for doc in docs[i:i_end]]
             # create unique IDs