Why is catching the exception not working?

Question

PHP

Good day.
Made this code:

<?php
function foo(
      string $m): void{
  if(!is_string($m)){
    throw new Exception('не строка');
  }
}
try{
  foo(15);
}
catch(Exception $e){
  echo 'перехваченное исключение', $e->getMessage();
}

I have a blank page in the browser, why?
And another question: is it possible to catch all types of exceptions at once using Throwable? Or are there other ways (without listing all types)?
Thanks for the replies.