Update app.py

app.py

@@ -135,10 +135,16 @@ def split_biomodels(antimony_file_path):
 def create_vector_db(final_items):
     global db
     client = chromadb.Client()
-    db = client.create_collection(
-        name="BioModelsRAG",
-        metadata={"hnsw:space": "cosine"}
-    )
+    collection_name = "BioModelsRAG"
+    try:
+        db = client.create_collection(
+            name=collection_name,
+            metadata={"hnsw:space": "cosine"}
+        )
+    except UniqueConstraintError:
+        print(f"Collection '{collection_name}' already exists.")
+        collection = db.get_collection(name=collection_name)
+    
     documents = []
 
     from llama_cpp import Llama