Force Block Style to use Default

force-block-style-use-default.js

// TODO: We should make a little function that handles this by reading the defaults from the block.json.
let blockProps = useBlockProps( {
    className: 'my-block-name',
} );

let style = blockProps['className'].split( ' ' ).filter( className => className.startsWith( 'is-style-' ) )[0] || '';

// The default style does not automatically apply. Fix that.
if ( ! style ) {
    style = 'is-style-default';
    blockProps['className'] += ' ' + style;
}