fix typo

app.py

@@ -3,11 +3,11 @@ title = "Character aware stable difusion"
 description = "This is a demo o a character aware diffusion model"
 def infer_sd(prompt, negative_prompt, image):
     # your inference function for stable diffusion control 
-    return im
+    return None
 
 def infer_charr_sd(prompt, negative_prompt, image):
     # your inference function for charr stable difusion control 
-    return im
+    return None
 
 with gr.Blocks(theme='gradio/soft') as demo:
     gr.Markdown("## Character aware stable difusion")