Description

In xASL_module_ASL it can happen that the loaded image is empty. This should lead to an error in the following part, but shouldn't crash the pipeline. I suggest this simple edit:

Old:

%% Skip processing if invalid image

tempASL = xASL_io_Nifti2Im(x.P.Path_ASL4D);
if max(tempASL(:))==0 || numel(unique(tempASL(:)))==1
    error('Invalid ASL image');
end

New:

%% Skip processing if invalid image
tempASL = xASL_io_Nifti2Im(x.P.Path_ASL4D);
if isempty(tempASL) || (max(tempASL(:))==0 || numel(unique(tempASL(:)))==1)
    error('Invalid ASL image');
end

Requirements

Optional: add bug requirements here

How to test

Optional: insert description about how to test the code changes here

Release notes

Stop pipeline from crashing for empty NIfTI files.