Invalid and unused line in slicerio/segmentation.py for overlapping segmentations

[AFanthomme]

Hi,

In slicerio/segmentation.py, line 503 (executed only in case of overlapping segments) reads:
nan_column = np.array()

and at execution raises a TypeError in numpy (tested in 1.26) since array expects an 'object' argument at construction https://numpy.org/doc/2.1/reference/generated/numpy.array.html

Since nan_columns appears unused in the rest of the script, deleting this line allows it to work with overlapping segments and should not have any consequence for legacy users.

Best regards and thanks for the tool !