Index: src/wp-includes/meta.php
===================================================================
--- src/wp-includes/meta.php	(revision 37932)
+++ src/wp-includes/meta.php	(working copy)
@@ -1030,6 +1030,10 @@
 		'show_in_rest'      => false,
 	);
 
+	if ( ! is_array( $args ) ) {
+		$args = array();
+	}
+
 	$passed_args = array_slice( func_get_args(), 2 );
 
 	// There used to be individual args for sanitize and auth callbacks