Cannot open "Settings" dialog in Views UI - ViewsProximityFilter.php on line 63 Warning: Undefined array key "views_filter"

Problem/Motivation

I have a view where (not sure now), the $context['views_filter'] is not set at all when trying to getAvailableLocationOptions in ViewsProximityFilter.php.

I think the code

    if ($context['views_filter'] ?? FALSE) {
      return $options;
    }

introduces a logic bug (came from commit f51efad69). This returns FALSE if context['views_filter'] is not set, which allows it to continue to the code below, which fails when it tries to check $filter !== $context['views_filter']

I believe we need something like:

    if (empty($context['views_filter'])) {
      return $options;
    }

The let's me access my Settings form in the Views UI again.