Using Magento 2 I created a cms static block that points to
{{block class="Inchoo\ModalOverlay\Block\etc" template="modal_overlay.phtml"}}
I followed this guide on how to create the modal
https://inchoo.net/magento-2/magento-2-how-to-display-static-block-content-in-modal-overlay/
but once its saved I get a error msg "We're sorry, an error has occurred while generating this content."
turned on developer mode and I dont get any other details about the error.