WTV Project Category Must Be Assigned

publish-halt.js

jQuery('#publish').on('click', function(e){
  
  var $checkboxes = jQuery('#project_categorieschecklist input[name*="project_categories"][type="checkbox"]');
  var checked = false;
  
  var loop = jQuery.each( $checkboxes, function( i, el ){
    if ( true == jQuery( el ).prop('checked') ){
      checked = true;
      return false; // bail early
    }
  });
  
  if ( false === checked ){
    e.preventDefault(); 
    alert('You must assign a category for this project!'); 
  }
  
});

Categories must be assigned before publishing / updating a project.