diff --git a/lotus/vector_store/chroma_vs.py b/lotus/vector_store/chroma_vs.py
index d05b1e4..3735f79 100644
--- a/lotus/vector_store/chroma_vs.py
+++ b/lotus/vector_store/chroma_vs.py
@@ -1,4 +1,4 @@
-from typing import Any, Callable, Union
+from typing import Any, Callable, Mapping, Union
 
 import numpy as np
 import pandas as pd
@@ -11,14 +11,16 @@
 
 try:
     import chromadb
+    from chromadb import ClientAPI 
     from chromadb.api import Collection
+    from chromadb.api.types import IncludeEnum 
 except ImportError as err:
     raise ImportError(
         "The chromadb library is required to use ChromaVS. Install it with `pip install chromadb`"
     ) from err 
 
 class ChromaVS(VS):
-    def __init__(self, client: chromadb.Client, embedding_model: Callable[[pd.Series | list], NDArray[np.float64]], max_batch_size: int = 64):
+    def __init__(self, client: ClientAPI, embedding_model: Callable[[pd.Series | list], NDArray[np.float64]], max_batch_size: int = 64):
         """Initialize with ChromaDB client and embedding model"""
         super().__init__(embedding_model)
         self.client = client
@@ -45,7 +47,7 @@ def index(self, docs: pd.Series, collection_name: str):
         
         # Prepare documents for addition
         ids = [str(i) for i in range(len(docs_list))]
-        metadatas = [{"doc_id": i} for i in range(len(docs_list))]
+        metadatas: list[Mapping[str, Union[str, int, float, bool]]] = [{"doc_id": int(i)} for i in range(len(docs_list))]
         
         # Add documents in batches
         batch_size = 100
@@ -98,14 +100,14 @@ def __call__(
             results = self.collection.query(
                 query_embeddings=[query_vector.tolist()],
                 n_results=K,
-                include=['metadatas', 'distances']
+                include=[IncludeEnum.metadatas, IncludeEnum.distances]
             )
 
             # Extract distances and indices
             distances = []
             indices = []
             
-            if results['metadatas']:
+            if results['metadatas'] and results['distances']:
                 for metadata, distance in zip(results['metadatas'][0], results['distances'][0]):
                     indices.append(metadata['doc_id'])
                     # ChromaDB returns squared L2 distances, convert to cosine similarity
@@ -121,8 +123,8 @@ def __call__(
             all_indices.append(indices)
 
         return RMOutput(
-            distances=np.array(all_distances, dtype=np.float32),
-            indices=np.array(all_indices, dtype=np.int64)
+            distances=np.array(all_distances, dtype=np.float32).tolist(),
+            indices=np.array(all_indices, dtype=np.int64).tolist()
         )
 
     def get_vectors_from_index(self, collection_name: str, ids: list[int]) -> NDArray[np.float64]:
@@ -130,13 +132,18 @@ def get_vectors_from_index(self, collection_name: str, ids: list[int]) -> NDArra
         if self.collection is None or self.collection_name != collection_name:
             self.load_index(collection_name)
 
+
+        if self.collection is None:  # Add this check after load_index
+            raise ValueError(f"Failed to load collection {collection_name}")
+
+
         # Convert integer ids to strings for ChromaDB
         str_ids = [str(id) for id in ids]
         
         # Get embeddings from ChromaDB
         results = self.collection.get(
             ids=str_ids,
-            include=['embeddings']
+            include=[IncludeEnum.embeddings]
         )
 
         if not results['embeddings']: