A signal query authoring functions will be executed as part of the directive instance construction. This happens before we could create a query instance and execute the template’s creation mode to collect any matches. As a consequence, there is a period of time where the signal instance was created (and can be read) but no query results could have been collected. By default Angular will return `undefined` (for child queries) or an empty array (for children queries) before results are available. Required queries will throw if accessed at this point.