Add a name your price product to an Event Ticket Plus Ticket group

add_products_to_tickets.php

<?php
//add this to wootickets/tickets.php
//add after the big foreach ( $tickets as $ticket ) 
//requires ACF to set a custom field that pulls the product you want to add with a post object field
//requires WooComerce Name Your Price plugin

if( 0 < count( get_field( 'add_products_to_tickets' ) ) ): 
			foreach( get_field( 'add_products_to_tickets' ) as  $extra_product ):
				$product = wc_get_product( $extra_product );
				if( class_exists('WC_Name_Your_Price')){
					$nyp = get_post_meta( $extra_product->ID, '_nyp', true);
					if( 'yes' === $nyp){
						?>
							<tr class="woocomerce" data-product-id="<?php echo $extra_product->ID ?>">
							<td>
							  <input type="hidden" name="quantity_<?php echo $extra_product->ID ?>" value="1" title="Qty" class="qty">
							</td>
							<td><?php echo $product->name ?></td>
							<td>
								<span class="woocommerce-Price-amount amount">
									<?php echo WC_Name_Your_Price_Helpers::get_price_input( $extra_product->ID, $prefix ); ?>
								</span>
							</td>
							<td>
								<?php echo $product->post->post_excerpt ?>
							</td>
							</tr>
							<input type="hidden" name="product_id[]" value="<?php echo $extra_product->ID ?>">
						<?php
					} else {
						//add more products here
					}
				}
		endforeach; endif; ?>

Tried but get a
Warning: Invalid argument supplied for foreach() in /*****/tribe-events/wootickets/tickets.php on line 210
Line in question is
foreach( get_field( 'add_products_to_tickets' ) as $extra_product ):
Can you give a little more direction on the ACF config and exactly where and how to add this to WP 4.9.4 - events tickets plus / views
This would be a great solution for many people until MTribe adds this feature or supports NYP for WooCommerce