Cannot modify header information – header already sent (CPT related)

Question

I don’t know if it’ll help but try putting the supported functions into their own variable array like you do with labels.

$supports = array( 
     'title',
     'editor'
);

Then, under $args, use 'supports' => $supports.

I use that for ‘labels’, ‘supports’ and ‘taxonomies’.

Should also note that it’s good practice to make your variables a bit more unique to the post-type. So $revw_labels, $revw_supports, $revw_taxonomiesand make sure you input custom text_domains instead of using the generic placeholder. That’d be the text domain of either your plugin or theme.