Recursive function return issue - php

Question

I'm writing a recursive function like below:
private function getManager($employee)
{
$manager = $employee->manager;
if ($manager) {
array_push($this->managers, $manager->id);
$this->getManager($manager);
}
return;
}
This function receive an employee and find his manage. If find a manage, then push manager id into an array ($this->managers on line 5). Then call this function recursively and pass manager as an employee. If no manager found on line 3, then this function just return (line 8).
So my question is, is their any problem if i'm not return the recursive call at line 6 ($this->getManager($manager);)

Answer 1

Not sure if this is what you think, but it works.
function getManagers($employee)
{
$managers = [];
if (isset($employee->manager)) {
array_push($managers, $employee->manager->id);
array_push($managers, ...getManagers($employee->manager));
}
return $managers;
}

Answer 2

No, there is absolutely no benefit in writing the empty return. The method will halt regardless of the existence of the return.
Please observe the two methods below which show identical, error-less outcomes regardless of the return.
Code: (Demo)
class Management
{
private $managers = [];
function __construct($managerTree)
{
$this->getManager($managerTree);
var_export($this->managers);
echo "\n---\n";
$this->managers = [];
var_export($this->managers);
echo "\n---\n";
$this->getManager2($managerTree);
var_export($this->managers);
}
private function getManager(?object $employee): void
{
$manager = $employee->manager;
if ($manager) {
array_push($this->managers, $manager->id);
$this->getManager($manager);
}
return;
}
private function getManager2(?object $employee): void
{
$manager = $employee->manager;
if ($manager) {
array_push($this->managers, $manager->id);
$this->getManager($manager);
}
}
}
new Management(
(object) [
'id' => 3,
'manager' => (object) [
'id' => 2,
'manager' => (object) [
'id' => 1,
'manager' => null
]
]
]
);
Output:
array (
0 => 2,
1 => 1,
)
---
array (
)
---
array (
0 => 2,
1 => 1,
)