I’m creating a widget that’s compatible with Elementor Pro but I’m getting a Fatal Error: Uncaught TypeError: Elementor\Controls_Stack::sanitize_settings(): Argument #1 ($settings) must be of type array, null given. I’m trying to create a select field and the array I’m returning are the options for the select field. I have other select fields that work just fine with a returned array but I can’t figure out why this one doesn’t work. I’ve done a var_dump of the variable to verify it is an array and to see the contents of the array. Everything looks fine. I also did a test by manually creating a simple array to return and that worked. Here is my function:

/**
 * Get a list of the custom field names from the selected post type
 */
protected function get_post_fields(){
    /***** This code works fine but isn't what I need***************
    $post_fields = [
        'default' => esc_html__( 'Default', 'OWSM-table-widget' ),
        'yes' => esc_html__( 'Yes', 'OWSM-table-widget' ),
        'no' => esc_html__( 'No', 'OWSM-table-widget' ),
    ];
    return $post_fields; 
    ***************************************************************/
    //Get the selected post type
    $my_settings = $this->get_settings_for_display(); 
    $selected_post_type = $my_settings['data_source'];

    //Array to store field names
    $field_names = array();

    //Check to make sure there is a selected post type
    if (!$selected_post_type) {
        return;
    }
    
    //Get the selected post type, loop through and get custom post field names
    $wanted_posts = new WP_Query(array('post_type' => $selected_post_type));
            if($wanted_posts->have_posts()) : 
                while($wanted_posts->have_posts()) : $wanted_posts->the_post();
               
                // Get all the custom data 
                $getPostCustom = get_post_custom(); 
                //Store the names of the custom fields in an array 
                foreach($getPostCustom as $name=>$value) {
                    if (strpos($name, "_") !== 0){          
                       $field_names[$name] = esc_html__($name, 'OWSM-table-widget');
                    }
                }
                endwhile;
                
            endif;
        // Return to the current page's main query
        wp_reset_query();
        //Return the array of custom fields for the specified post type
        return $field_names;
}

Here’s the var_dump of the manually created array $post_fields:
array(3) { [“default”]=> string(7) “Default” [“yes”]=> string(3) “Yes” [“no”]=> string(2) “No” }

And here’s the var_dump of the $field_names array created with the loop:
array(5) { [“city”]=> string(4) “city” [“nights_of_play”]=> string(14) “nights_of_play” [“contact”]=> string(7) “contact” [“email”]=> string(5) “email” [“phone”]=> string(5) “phone” }

Both arrays have the exact same structure but the $field_names array gives me the error. Any suggestions?