Handle missing field_link_provider

Problem/Motivation

After updating from WxT 5.6.1 to 6.3.0, the following message appears in the page footer:

InvalidArgumentException: Field field_link_provider is unknown. in Drupal\Core\Entity\ContentEntityBase->getTranslatedField() (line 630 of core/lib/Drupal/Core/Entity/ContentEntityBase.php).

This error message is triggered in wxt_bootstrap_preprocess_paragraph() due to this line:

$field_definition = $variables['paragraph']->getFieldDefinition('field_link_provider');

I note that field_link_provider exists in WxT 6.3.0 on config/optional. There is no mention of it in WxT 5.6.1.

Proposed resolution

There should be a guard in wxt_bootstrap that checks for field_link_provider before calling ::getFieldDefinition().

Perhaps there should also be an update hook to create field_link_provider.

Remaining tasks

Confirm the correct solution. Implement.

User interface changes

None.

API changes

None.

Data model changes

None.