`AttributeError` when extracting multiple ROIs on a single image, if more than one image is selected

[PierreRaybaut]

How to reproduce:

• Select more than one image
• Select "Processing > ROI extraction"
• Enable "Extract all ROIs in a single image object"
• Click on "OK"

Example of extraction:

Traceback:

Traceback (most recent call last):
  File "C:\Dev\Projets\DataLab\cdl\core\gui\processor\catcher.py", line 50, in wng_err_func
    result = func(*args)
             ^^^^^^^^^^^
  File "C:\Dev\Projets\DataLab\cdl\computation\image\__init__.py", line 773, in extract_multiple_roi
    src2.roi = src2.roi.from_params(src2, group)
               ^^^^^^^^^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'from_params'