warnings issued on 'drush' command using PHP 7.X

Problem/Motivation

General description of the issue

After switching to PHP7 (in this specific case is PHP 7.2.19) we noticed that drush cc all command would clog the output with many repeated warnings

Illegal string offset 'type' page.admin.inc:163   [warning]
Illegal string offset 'type' page.admin.inc:166   [warning]
[...]

this behaviour doesn't happen using PHP 5.6 (specifically PHP 5.6.40).

Relevant information about software/versions

Issue presented itself in Unix/Linux shell environment (bash/zsh) using

• drush 8.2.3
• Drupal 7.67
• PHP 7.2.19
• ctools 7.x-1.15
• ctools_custom_content 7.x-1.15

Proposed resolution

We patched ctools page_manager/plugins/tasks/page.admin.inc file adding some minimal check upon $menu variable being an array (apparently, when loaded from a drush call it is not):

code

  if (empty($menu['type'])) {
    $menu['type'] = 'none';
  }

became

  if (is_array($menu) && empty($menu['type'])) {
    $menu['type'] = 'none';
  }
  else if(!is_array($menu)) {
    $menu = ['type' => 'none'];
  }
  else if(empty($menu['type'])) {
   $menu['type'] = 'none';
  }