Fatal error: Uncaught TypeError: SimpleXMLElement::addChild(): Argument #2 ($value) must be of type ?string, float given in /var/www/dev.image.plum.monster/pages/sitemap.php on line 90

TypeError: SimpleXMLElement::addChild(): Argument #2 ($value) must be of type ?string, float given in /var/www/dev.image.plum.monster/pages/sitemap.php on line 90

Call Stack:
    0.0000     431128   1. {main}() /var/www/dev.image.plum.monster/root/handler.php:0
    0.0002     448440   2. require('/var/www/dev.image.plum.monster/pages/sitemap.php') /var/www/dev.image.plum.monster/root/handler.php:50
    0.0008     450760   3. SimpleXMLElement->addChild($qualifiedName = 'priority', $value = 0.8) /var/www/dev.image.plum.monster/pages/sitemap.php:90