Fix component validation issues

Problem/Motivation

I'm using Drupal 11 and a Drupal CMS project. The Civic Theme is installed with a subtheme. The subtheme is currently enabled. Regardless of which is the default theme, I'm getting a page error when I open the site.

The website encountered an unexpected error. Try again later.

Drupal\Core\Render\Component\Exception\InvalidComponentException: [civictheme:text-icon/is_new_window] NULL value found, but a boolean or an object is required. This may be because the property is empty instead of having data present. If possible fix the source data, use the |default() twig filter, or update the schema to allow multiple types.. [civictheme:text-icon/is_external] NULL value found, but a boolean or an object is required. This may be because the property is empty instead of having data present. If possible fix the source data, use the |default() twig filter, or update the schema to allow multiple types.. [civictheme:text-icon/icon] NULL value found, but a string or an object is required. This may be because the property is empty instead of having data present. If possible fix the source data, use the |default() twig filter, or update the schema to allow multiple types.. in Drupal\Core\Theme\Component\ComponentValidator->validateProps() (line 242 of core/lib/Drupal/Core/Theme/Component/ComponentValidator.php).

These are common with many lower-level components including heading, field, and link.

For example:

Drupal\Core\Render\Component\Exception\InvalidComponentException: [civictheme:skip-link/theme] NULL value found, but a string or an object is required.

Drupal\Core\Render\Component\Exception\InvalidComponentException: [civictheme:heading/level] Integer value found, but a string is required. 

Steps to reproduce

1. Install CivicTheme.
2. Set up component validation as described here * Make sure that the justinrainbow/json-schema library is in your vendor/ directory
3. Install devel module
4. [optional] Set up your local environment to use a settings.local file, based on Drupal's default example.settings.local.php file

(* Note that other modules or composer configuration could also include the justinrainbow/json-schema library. For example, it is a dependency of acquia-cms-starterkit)

Installing devel module seems to be the key to triggering these errors. Setting up your settings.local will just make this error appear directly on the screen rather than the standard WSOD message.

Proposed resolution

Fix component validation issues.

Note that setting enforce_prop_schemas: false in the subtheme's info file does not prevent these errors from occurring. See: Documentation on component data validation