False positive: isset on nested associative arrays

[Alban-io]

Bug report

+--------------------------------------------------------------+
| Line | test.php                                              |
+--------------------------------------------------------------+
| 23   | Unreachable statement - code above always terminates. |
+--------------------------------------------------------------+

Code snippet that reproduces the problem

➡️ https://phpstan.org/r/053b9b77-618e-4af2-8105-c2a572945565

<?php declare(strict_types = 1);

$fun = function (): array {
    return [
        ['group_id' => 'a', 'user_id' => 'id1'],
        ['group_id' => 'a', 'user_id' => 'id2'],
        ['group_id' => 'a', 'user_id' => 'id3'],
        ['group_id' => 'b', 'user_id' => 'id4'],
        ['group_id' => 'b', 'user_id' => 'id5'],
        ['group_id' => 'b', 'user_id' => 'id6'],
    ];
};

$orders = $fun();

$result = [];
foreach ($orders as $order) {
    // no error trigger with this statement
    // if (isset($result[$order['group_id']])) {
    if (isset($result[$order['group_id']]['users'])) {
        $result[$order['group_id']]['users'][] = $order['user_id'];
        continue;
    }

    $result[$order['group_id']] = [
        'users' => [
            $order['user_id'],
        ],
    ];
}

Expected output

 [OK] No errors 

[phpstan-bot]

@Alban-io After the latest commit in dev-master, PHPStan now reports different result with your code snippet:

@@ @@
-23: Unreachable statement - code above always terminates.
+No errors

[github-actions]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.