Term weight is a string?

I am getting a taxonomy through a REST plugin, and I return it as an array keyed by id, since I also have to access it by id. But when I display the values in an HTML select, I have to order it by weight, so I am ordering it in a javascript function. I got unexpected results, and I traced it to the fact that Term::weight() apparently returns a string rather than an int, or at least this is what this test code shows:

use Drupal\taxonomy\Entity\Term;
[...]
    $term = Term::load(407) ;
    echo $term->name->value, " has weight ", $term->getWeight(), PHP_EOL ;
    echo "and it is a ", gettype($term->getWeight()), PHP_EOL ;

The above code is in a drush script, and when I run it I get

# /var/www/mysite/svil/vendor/bin/drush scr test.php 
Location to be defined has weight 0
and it is a string

The documentation for Term::getWeight() claims that it returns an integer. I looked at the code, but the implementation is simply

  public function getWeight() {
    return $this->get('weight')->value;
  }

which says nothing about the type of the result.

Of course I can simply apply intval(), but I would like to know what's going on here.