The problem occurs when the value is_numeric but is also a string.
Steps to recreate:
$template = Codewithkyrian\Jinja\Template('{{ test }}');
$template->render([ 'test' => '60' ]);
Result:
Codewithkyrian\Jinja\Runtime\NumericValue::__construct(): Argument #1 ($value) must be of type int|float, string given, called in vendor\codewithkyrian\jinja-php\src\Core\Environment.php on line 161.