Isset check is breaking the array-shape definition

[VincentLanglet]

https://psalm.dev/r/18d1dfabd5

After the isset check, every values are considered as mixed by psalm.

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/18d1dfabd5

<?php

/**
 * @param array{
 *     label?: string|false|null,
 *     type?: string,
 * }&array<string, mixed> $i
 */
function foo(array $i) {
    /** @psalm-trace $a */
    $a = $i;
    
    if (isset($i['type'])) {
    }
        
    /** @psalm-trace $a */
    $a = $i;
}

Psalm output (using commit 902a019):

INFO: Trace - 11:5 - $a: array{label?: false|null|string, type?: string, ...<string, mixed>}

INFO: Trace - 17:5 - $a: array{label?: false|mixed|null|string, type?: mixed|string, ...<string, mixed>}

INFO: UnusedVariable - 11:5 - $a is never referenced or the value is not used

INFO: UnusedVariable - 17:5 - $a is never referenced or the value is not used

INFO: MissingReturnType - 9:10 - Method foo does not have a return type, expecting void