Update app.py

app.py

@@ -24,6 +24,8 @@ def infer(color_prompt, phone_type_prompt, design_prompt):
     return image, message
 
 def save_design(image):
+    if image is None:
+        return "No image to save. Please generate a design first."
     file_path = "saved_design.png"
     image.save(file_path)
     return f"Design saved as {file_path}!"