Update app.py

app.py

@@ -71,7 +71,7 @@ async def generate_command(
 
         image_url_or_error = await generate_image_async(prompt, aspect_ratio.value)
         # await interaction.response.send_message(f"Error:{image_url_or_error}")
-        if image_url_or_error not None:
+        if image_url_or_error:
         # if image_url_or_error.startswith("http"):
             await interaction.followup.send(
                 # f"Here's your generated image based on the prompt '{prompt}' with aspect ratio {aspect_ratio.name}:\n{image_url_or_error}"