How can I solve this problem in the CSP feature extraction algorithm for EEG signal?

Dataset description:

Code:

% Calculate the covariance matrices for each class

cov_matrices = cell(1, 2);

disp(unique(labels));

disp(size(epochs));

for i = 1:2

if any(labels == i)

class_epochs = epochs(:, :, labels == i);

cov_matrices{i} = cov(class_epochs');

else

disp(['No data for class ', num2str(i)]);

end

end

Error: