using the controlnet pipeline without a controlnet selected throws an error

[ssube]

If you don't have any controlnets downloaded or don't have one selected in the web UI for some other reason, the menu will be empty and send an empty parameter to the server. When used with the controlnet pipeline, that throws an error:

TypeError: OnnxStableDiffusionControlNetPipeline.init() missing 1 required positional argument: 'feature_extractor'

There are two parts to this:

• if the controlnet pipeline has been selected, make sure a controlnet has also been selected (in the web UI, preferably)
• change the default pipeline for the img2img tab to be img2img