Expose errors

[abidlabs]

Instead of not replying, it would be better if errors were exposed

[SaboniAmine]

Which level of error would you like to expose ?
For instance, trying to query the stabilityai/stable-diffusion space, I get a gradio internal error :

    serialized_input = block.serialize(inputs[i])
AttributeError: 'Dataset' object has no attribute 'serialize'

But when querying the mirrored abidlabs/images space I might wait a long time to get no answer (understandable, with the current queue), or explicitely get an asyncio.exceptions.CancelledError much sooner.
The second might be caught and sent back to the channel as a timeout, but I don't know if users should be exposed to the first one as is.

[abidlabs]

Good point @SaboniAmine! How did you see the gradio internal error when you tried to query stabilityai/stable-diffusion space?

[abidlabs]

In terms of the second error, I think we should also expose the queue ETA when people first make a request to a particular Space. However, this should probably be a separate issue. Would you like to go ahead and create it?