when no chose, do not let use chose model

app.py

@@ -76,8 +76,9 @@ def create_application():
             if value in model.tasks
         ]
         if choices:
+            active = len(choices)>1
             return (
-                gr.update(choices=choices, value=choices[0], visible=True, label=f"Matching Mammal models ({len(choices)})",),
+                gr.update(choices=choices, value=choices[0], interactive=active, visible=True, label=f"Matching Mammal models ({len(choices)})",),
                 *visibility,
             )
         else: