Problem/Motivation
Currently it is not possible to exclude theme condition from evaluation. Though the select list with themes is not marked as required the user is always bound to select some theme because there is no "empty" option. For other condition plugins there is a workaround. For instance for Node bundle plugin you can uncheck all content types so the condition will always evaluate to TRUE. Same for User role condition plugin. And for Request path you can leave empty pages textarea.
Proposed resolution
Add "- Any -" option to theme select list of the plugin configuration form.
Enable current theme condition on block, because was removed on issue https://www.drupal.org/project/drupal/issues/2339151
API changes
The current theme condition is available on blocks and now there is a new option "- Any -" on the options.
Steps to reproduce:
- Edit/create a new block on Structure/Block Layout
- The current theme is not visible
- Apply the patch
- The current theme is available
![Configure theme condition on blocks]()
- There is a list of enabled themes to choose where to show the block with the "- Any -" condition. and is possible to negate the condition
![List conditional theme]()
