Full of Notice, unable to edit widget

As in subject. The theme is full of notice, that block updating of widget.
For example, editing post and uncheck “Hide AD content”, or leave unchecked show author, category, date or number of comment checkbox in widget data.

Here some example of blocking error. (please note that error are blocking also with WP_DEBUG false)

This on save post/page:
Notice: Undefined index: disable_ad in /path/wp-content/plugins/universal-google-adsense-and-ads-manager/includes/custom-fields/class-ugaam-post-field.php on line 81

This on edit widget:
[02-Sep-2019 17:30:41 UTC] PHP Notice: Undefined index: show_categories_meta in /path/wp-content/themes/cream-magazine/inc/widget/news-widgets/class-cream-magazine-news-widget-one.php on line 249
[02-Sep-2019 17:30:41 UTC] PHP Notice: Undefined index: show_author_meta in /path/wp-content/themes/cream-magazine/inc/widget/news-widgets/class-cream-magazine-news-widget-one.php on line 251
[02-Sep-2019 17:30:41 UTC] PHP Notice: Undefined index: show_date_meta in /path/wp-content/themes/cream-magazine/inc/widget/news-widgets/class-cream-magazine-news-widget-one.php on line 253
[02-Sep-2019 17:30:41 UTC] PHP Notice: Undefined index: show_cmnt_no_meta in /path/wp-content/themes/cream-magazine/inc/widget/news-widgets/class-cream-magazine-news-widget-one.php on line 255