Delete action for a Service Landing page or Service Sub Landing Page can trigger a PHP error.

[marcopagliarulo]

Trying to delete a Service Landing Page from the Content page, the error "Oops, something went wrong... " is shown to the user.
The root cause is located here https://github.com/localgovdrupal/localgov_services/blob/2.x/modules/localgov_services_navigation/src/EntityChildRelationshipUi.php#L143

Library should be an array of string, not a string, so when Drupal Core try to add the modal library, it generate a PHP error.

[andybroomfield]

Have replicated this issue, thanks for the report @marcopagliarulo