Found bug on Image component with sketch mode.

[fladdict]

Describe the bug

Sketch mode Image components returns errors in particular situation.
When people upload image but don't use drawing pen, and run input,
Enpty mask invoke error in processing_utils.py line 28.

Beter result is returning data like {image:imagePath, mask: None}

Seems need to fix somewhere around line 1332 of components.py

Is there an existing issue for this?

• I have searched the existing issues

Reproduction

1. Set Image Component to Sketch mode
2. Upload Image to Image Component
3. Don't draw anything
4. Press ok button to call function

Screenshot

No response

Logs

Traceback (most recent call last):
  File "/usr/local/lib/python3.7/dist-packages/gradio/routes.py", line 249, in run_predict
    fn_index, raw_input, username, session_state
  File "/usr/local/lib/python3.7/dist-packages/gradio/blocks.py", line 641, in process_api
    processed_input = self.preprocess_data(fn_index, raw_input, state)
  File "/usr/local/lib/python3.7/dist-packages/gradio/blocks.py", line 545, in preprocess_data
    processed_input.append(block.preprocess(raw_input[i]))
  File "/usr/local/lib/python3.7/dist-packages/gradio/components.py", line 1563, in preprocess
    mask_im = processing_utils.decode_base64_to_image(mask)
  File "/usr/local/lib/python3.7/dist-packages/gradio/processing_utils.py", line 28, in decode_base64_to_image
    content = encoding.split(";")[1]
AttributeError: 'NoneType' object has no attribute 'split'

System Info

piped recent version and testet with colab.

Severity

serious, but I can work around it