[Bug]: Broken txt2img

[Centurion-Rome]

Is there an existing issue for this?

• I have searched the existing issues and checked the recent builds/commits

What happened?

generated image won't save and display

Steps to reproduce the problem

1. Go to txt2img enter some prompt
2. Press 'generate"
3. see error:
   .
   "Error completing request:52, 1.82s/it]
   Arguments: ('school bus', '', 'None', 'None', 8, 16, False, False, 1, 1, 11, -1.0, -1.0, 0, 0, 0, False, 768, 1344, False, 0.7, 0, 0, 0, False, False, False, False, '', 'Illustration', 'svg', True, True, False, 0.5, True, 16, True, 16, 1, '', 0, '', True, True, False) {}
   Traceback (most recent call last):
   File "F:!AI\StableDiffusion\stable-diffusion-webui\modules\call_queue.py", line 45, in f
   res = list(func(*args, **kwargs))
   File "F:!AI\StableDiffusion\stable-diffusion-webui\modules\call_queue.py", line 28, in f
   res = func(*args, **kwargs)
   File "F:!AI\StableDiffusion\stable-diffusion-webui\modules\txt2img.py", line 49, in txt2img
   processed = process_images(p)
   File "F:!AI\StableDiffusion\stable-diffusion-webui\modules\processing.py", line 464, in process_images
   res = process_images_inner(p)
   File "F:!AI\StableDiffusion\stable-diffusion-webui\modules\processing.py", line 607, in process_images_inner
   images.save_image(image, p.outpath_samples, "", seeds[i], prompts[i], opts.samples_format, info=infotext(n, i), p=p)
   File "F:!AI\StableDiffusion\stable-diffusion-webui\modules\images.py", line 536, in save_image
   _atomically_save_image(image, fullfn_without_extension, extension)
   File "F:!AI\StableDiffusion\stable-diffusion-webui\modules\images.py", line 508, in _atomically_save_image
   image_format = Image.registered_extensions()[extension]
   KeyError: '.jpg'"

What should have happened?

image was generated and saved

Commit where the problem happens

685f963

What platforms do you use to access UI ?

No response

What browsers do you use to access the UI ?

No response

Command Line Arguments

--xformers

Additional information, context and logs

No response

[ataa]

Seems to be related to #5603