Import: Avoid counting an uncountable type when reading arguments passed to a script.

Props josephscott.
Fixes #42898.

git-svn-id: https://develop.svn.wordpress.org/trunk@42771 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/includes/class-wp-importer.php

@@ -281,6 +281,9 @@ class WP_Importer {
  */
 function get_cli_args( $param, $required = false ) {
 	$args = $_SERVER['argv'];
+	if ( ! is_array( $args ) ) {
+		$args = array();
+	}
 
 	$out = array();