Deprecated: addslashes(): Passing null to parameter → `WP_SQLite_DB->_real_escape( $str )`

[remcotolsma]

We noticed the following error:

Deprecated: addslashes(): Passing null to parameter #1 ($string) of type string is deprecated in sqlite-database-integration/wp-includes/sqlite/class-wp-sqlite-db.php on line 107

https://github.com/WordPress/sqlite-database-integration/blob/037f6efe3ac27e9cda668e6d13eb087ed5471bce/wp-includes/sqlite/class-wp-sqlite-db.php#L95-L108

I think that in certain cases null is passed to the _real_escape function.

In WordPress core they check on the type with is_scalar( $data ):

    /**
     * Real escape using mysqli_real_escape_string().
     *
     * @since 2.8.0
     *
     * @see mysqli_real_escape_string()
     *
     * @param string $data String to escape.
     * @return string Escaped string.
     */
    public function _real_escape( $data ) {
        if ( ! is_scalar( $data ) ) {
            return '';
        }

        if ( $this->dbh ) {
            $escaped = mysqli_real_escape_string( $this->dbh, $data );
        } else {
            $class = get_class( $this );

            wp_load_translations_early();
            /* translators: %s: Database access abstraction class, usually wpdb or a class extending wpdb. */
            _doing_it_wrong( $class, sprintf( __( '%s must set a database connection for use with escaping.' ), $class ), '3.6.0' );

            $escaped = addslashes( $data );
        }

        return $this->add_placeholder_escape( $escaped );
    }

https://github.com/WordPress/WordPress/blob/9fd435aa157ad7053cdcabed879b843342999ffe/wp-includes/class-wpdb.php#L1262-L1290

Maybe that should be added in this plugin too?