Description:
------------
When 'void' is specified as return type of arrow function, fatal error will be caused.

Even if it returns void, it will not be fatal error if the return type is not specified.

Test script:
---------------
function returnVoid(): void
{
}

var_dump(array_map(fn (int $n) => returnVoid(), [1, 2, 3]));
var_dump(array_map(fn (int $n): void => returnVoid(), [1, 2, 3]));

Expected result:
----------------
array(3) {
  [0]=>
  NULL
  [1]=>
  NULL
  [2]=>
  NULL
}
array(3) {
  [0]=>
  NULL
  [1]=>
  NULL
  [2]=>
  NULL
}

Actual result:
--------------
array(3) {
  [0]=>
  NULL
  [1]=>
  NULL
  [2]=>
  NULL
}
PHP Fatal error:  A void function must not return a value in php shell code on line 1