PHP Warning: Array to string conversion (with fix)

Error:
[29-Apr-2024 18:48:08 UTC] PHP Warning: Array to string conversion in /mywebsite.com/wp-content/plugins/wp-job-manager/includes/ui/class-ui-elements.php on line 99

Line 99 is:
'class' => join( ' ', [ $class, $args['class'] ] ),

Full function:

/**
 * Generate HTML for a button or action link.
 *
 * @param array  $args Button options.
 * @param string $class Base classname.
 *
 * @return string Button HTML.
 */
public static function button( $args, $class ) {

    if ( empty( $args ) ) {
        return '';
    }

    $args = wp_parse_args(
        $args,
        [
            'label'   => '',
            'url'     => '',
            'onclick' => '',
            'class'   => '',
        ]
    );

    if ( empty( $args['url'] ) ) {
        $args['url'] = '#';
    }

    $attrs = [
        'class' => join( ' ', [ $class, $args['class'] ] ),
        'href'  => esc_url( $args['url'] ),
    ];

    if ( ! empty( $args['onclick'] ) ) {
        $attrs['onclick'] = $args['onclick'];
        $attrs['role']    = 'button';
    }

    return '<a ' . self::html_attrs( $attrs ) . '><span>' . esc_html( $args['label'] ) . '</span></a>';
}

Suggested fix for line 99:
'class' => join(' ', array_filter(array_merge((array)$class, (array)$args['class']))),