Why does `setcookie` send header before throwing `Error` exception?

[Jair López <jair_lopez4321@xxxxxxxxxxx>]

Hello PHP team!

The following code:

	<?php
		class Foo {
		}

		setcookie('name', 'value', array(
			'expires' => 1,
			'path' => new Foo()
		));
	?>

throws an error message that goes like this:

	PHP Fatal error:  Uncaught Error: Object of class Foo could not be 
converted to string in ...
	Stack trace:
	#0 ...: setcookie()
	#1 {main}
	   thrown in ...

so I would expect no `Set-Cookie` header to be send because of this 
fatal error. However, after wrapping this code in a try/catch block, I 
noticed it actually sent the header:

	Set-Cookie: name=value; expires=Thu, 01-Jan-1970 00:00:01 GMT; Max-Age=0

It looks like the `Error` exception is thrown somewhere after sending 
the cookie header. Why does it work in this way? Is it ok?

The call above is almost a synonym for this invocation:

	setcookie('name', 'value', 1,  => new Foo());

Except that it does not send the cookie header.

I tested it with PHP 8.0.3 on an ArchLinux box; what follows is a test file:

	--TEST--
	setcookie() sends header before throwing `Error` exception
	--FILE--
	<?php
	ob_start();

	class Foo{
	}

	try {
		setcookie('name', 'value', array(
			'path' => new Foo()
		));
	} catch (\Error $e) {
		echo $e->getMessage() . "\n";
	}

	var_dump(headers_list());
	echo "Done\n";
	?>
	--EXPECTHEADERS--

	--EXPECTF--
	Object of class Foo could not be converted to string
	array(1) {
	  [0]=>
	  string(23) "X-Powered-By: PHP/8.0.3"
	}
	Done

Thank you very much for your help,

Regards,
Jair López