Update generate_caption function to return a placeholder message when no control image is provided, and initialize space in app_v4.py

app_v4.py

@@ -85,7 +85,7 @@ def combine_caption_focus(caption, focus):
 
 def generate_caption(control_image):
     if control_image is None:
-        return None, None
+        return "Waiting for control image..."
     
     # Generate a detailed caption
     mcaption = model.caption(control_image, length="short")
@@ -239,4 +239,5 @@ with gr.Blocks(title="FLUX Turbo Upscaler", fill_height=True) as demo:
         outputs=[prompt]
     )
 
+init_space()
 demo.launch(show_error=True)