Upgrade: `$wpdb->get_col_length()` sanity check: bail on unexpected return value.

See #32165.


git-svn-id: https://develop.svn.wordpress.org/trunk@32429 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/includes/upgrade.php

@@ -1448,6 +1448,11 @@ function upgrade_430() {
 
 	if ( $wp_current_db_version < 32364 ) {
 		$content_length = $wpdb->get_col_length( $wpdb->comments, 'comment_content' );
+
+		if ( is_wp_error( $content_length ) ) {
+			return;
+		}
+
 		if ( false === $content_length ) {
 			$content_length = array(
 				'type'   => 'byte',