Show gallery only if has content

Hi, I need to show que thumbnail image if the gallery is empty, and the gallery if it has content.

I’ve tried with this:

function portfolio_image() {

	if( function_exists( 'easy_image_gallery' ) ) {
		echo easy_image_gallery();
	}else{
		echo '<div class="portfolio-image">'. genesis_get_image( array( 'size' => 'portfolio_entry' ) ) . '</div>';
	}
}
add_action( 'genesis_after_entry_content', 'portfolio_image' );

But it gets the gallery when has content, and nothing when hasn’t.

Any help please?

https://wordpress.org/plugins/easy-image-gallery/