WP_DEBUG Undefined index: mapquest_api_key

Upon initial install on fresh install:

PHP Notice:  Undefined index: mapquest_api_key in /wp-content/plugins/leaflet-maps-marker/leaflet-maps-marker.php on line 733
PHP Stack trace:
PHP   1. {main}() /index.php:0
PHP   2. require() /index.php:17
PHP   3. require_once() /wp-blog-header.php:19
PHP   4. include() /wp-includes/template-loader.php:74
PHP   5. get_header($name = *uninitialized*) /wp-content/themes/twentyseventeen/front-page.php:15
PHP   6. locate_template($template_names = *uninitialized*, $load = *uninitialized*, $require_once = *uninitialized*) /wp-includes/general-template.php:41
PHP   7. load_template($_template_file = *uninitialized*, $require_once = *uninitialized*) /wp-includes/template.php:647
PHP   8. require_once() /wp-includes/template.php:688
PHP   9. wp_head() /wp-content/themes/twentyseventeen/header.php:22
PHP  10. do_action($tag = *uninitialized*, $arg = *uninitialized*) /wp-includes/general-template.php:2614
PHP  11. WP_Hook->do_action($args = *uninitialized*) /wp-includes/plugin.php:453
PHP  12. WP_Hook->apply_filters($value = *uninitialized*, $args = *uninitialized*) /wp-includes/class-wp-hook.php:310
PHP  13. call_user_func_array:{/wp-includes/class-wp-hook.php:286}(*uninitialized*, *uninitialized*) /wp-includes/class-wp-hook.php:286
PHP  14. wp_enqueue_scripts(*uninitialized*) /wp-includes/class-wp-hook.php:286
PHP  15. do_action($tag = *uninitialized*, $arg = *uninitialized*) /wp-includes/script-loader.php:1447
PHP  16. WP_Hook->do_action($args = *uninitialized*) /wp-includes/plugin.php:453
PHP  17. WP_Hook->apply_filters($value = *uninitialized*, $args = *uninitialized*) /wp-includes/class-wp-hook.php:310
PHP  18. call_user_func_array:{/wp-includes/class-wp-hook.php:286}(*uninitialized*, *uninitialized*) /wp-includes/class-wp-hook.php:286
PHP  19. Leafletmapsmarker->lmm_frontend_enqueue_scripts(*uninitialized*) /wp-includes/class-wp-hook.php:286