Update app.py

app.py

@@ -31,7 +31,7 @@ def inference_t5(input_text, selected_model):
     
 # Functions for model-based tasks
 def perform_binary_classification(input_text, selected_model):
-    if 'turna' in selected_model:
+    if (selected_model is not None) and ('turna' in selected_model):
         return inference_t5(input_text, selected_model)
         
     model = pipeline(model=f'gokceuludogan/{selected_model}')