Fix another issue with model

app.py

@@ -83,12 +83,12 @@ def bot(history, model_name, oepnai_api_key,
     prompt_html = template_html.render(documents=documents, query=query)
 
 
-    if model_name == "HuggingFace":
+    if model_name in hf_models:
          generate_fn = generate_hf
-    elif model_name == "OpenAI":
+    elif model_name in openai_models:
          generate_fn = generate_openai
     else:
-         raise gr.Error(f"API {model_name} is not supported")
+         raise gr.Error(f"Model {model_name} is not supported")
     
 
     history[-1][1] = ""