[Resolved] array_filter(): Argument #1 ($array) must be of type array, false given

Background of the issue:
I am encountering a persistent issue with an import script that fails every time it runs. The script throws the following error: Fatal error: Uncaught TypeError: array_filter(): Argument #1 ($array) must be of type array, false given in wp-content/plugins/sitepress-multilingual-cms/classes/translation-jobs/class-wpml-element-translation-package.php:319. As a current workaround, we patched the above line with the following code:

$custom_fields_values = array_values( array_filter( get_post_meta( $post->ID, $key ) ?? [] ) );

. According to the get_post_meta documentation, false will be returned for invalid post_ids and is therefore a (somewhat) valid response from `get_post_meta` should be handled accordingly and not result in a fatal error.

Symptoms:
The import script fails every time it runs, throwing a Fatal error: Uncaught TypeError: array_filter(): Argument #1 ($array) must be of type array, false given.

Questions:
Why does the import script fail with the error: array_filter(): Argument #1 ($array) must be of type array, false given?
Is the workaround provided a valid solution to handle the false return value from get_post_meta?