I edited a date facet and changed it to use the processor from this module.
I then reloaded the View that uses this facet and got this crash:
TypeError: str_starts_with(): Argument #1 ($haystack) must be of type string, array given in str_starts_with() (line 50 of modules/contrib/facets/src/Plugin/facets/query_type/SearchApiString.php).
Drupal\facets\Plugin\facets\query_type\SearchApiString->execute() (Line: 167)
Drupal\facets\FacetManager\DefaultFacetManager->alterQuery(Object, 'search_api:views_embed__localgov_directory_channel__node_embed') (Line: 51)
Drupal\facets\EventSubscriber\SearchApiSubscriber->queryAlter(Object, 'search_api.query_pre_execute', Object)
Postponed: needs info
1.0
Code
The problem is DateRangeProcessor:preQuery() which calls
$facet->setActiveItems($active_items);
and $active_items must be an array of strings. Instead, it's building an array of arrays:
$item = [
date('U', 0),
date('U', strtotime('+100 years')),
];