Fix reshape error in render_blobs when cmaprange min equals max

[Copilot]

When using a custom colormap and cmaprange(1) == cmaprange(2), map_function returned a scalar instead of an array matching the shape of the input Z, causing a fatal reshape mismatch on cm(round(w),:).

Changes

• map_function: Multiply the constant mid-range value by ones(size(c)) so the output always matches the shape of the input, regardless of the x1 == x2 branch:

  % Before
  range_val = (y2-y1)/2;
  % After
  range_val = (y2-y1)/2 * ones(size(c));

• customcolormap branch: Add w(isnan(w)) = 1 after map_function to clamp NaN values in w (which arise from NaN entries in Z produced by out-of-range interp2 results) before they are used as array indices into cm.

Original prompt

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This section details on the original issue you should resolve

<issue_title>error on render_blobs</issue_title>
<issue_description>Hi,
I get the following error after running z_batch_publish_analyses('contrasts'), it doesn't happen with older version but since late 2024 after update:

Error using reshape
Number of elements must not change. Use [] as one of the size inputs to automatically calculate the appropriate size for that dimension.

Error in render_blobs (line 645)
slicecdat = reshape(cm(round(w),:),[size(Z),3]);

Error in fmridisplay/addblobs (line 378)
[blobhan, cmaprange, mincolor, maxcolor] = render_blobs(currentmap, obj.montage{i}, obj.SPACE, varargin{:});

Error in region/montage (line 394)
o2 = addblobs(o2, obj(i), varargin{:}, 'wh_montages', i, 'noverbose');

Error in c_univariate_contrast_maps (line 89)
o3 = montage(r, 'colormap', 'regioncenters');

Error in run (line 91)
evalin('caller', strcat(script, ';'));

Error in z_batch_coverage_and_contrasts (line 28)
run(scriptname); % Run from master script, not local script. This script should not need to be edited for individual studies.

Thanks </issue_description>

<agent_instructions>Try to find the source of the error.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes error on render_blobs #65

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