Update app.py

app.py

@@ -368,9 +368,14 @@ def explainability(_):
     return shap_path, lime_path
 
 # Define this BEFORE the Gradio app layout
+
 def update_target_choices():
     global df_global
-    return gr.update(choices=df_global.columns.tolist())
+    if df_global is not None:
+        return gr.update(choices=df_global.columns.tolist())
+    else:
+        return gr.update(choices=[])
+
 
 with gr.Blocks() as demo:
     gr.Markdown("## 📊 AI-Powered Data Analysis with Hyperparameter Optimization")