Unexpected TypeDoesNotContainType with optional array keys

[weirdan]

https://psalm.dev/r/d082e5d948
Expected: no issue, as $d['r'] may be empty (not initialized)

[psalm-github-bot]

I found these snippets:

https://psalm.dev/r/d082e5d948

<?php
  
$d = [];
if (!rand(0,1)) {
  $d['r'] = 'a';
}

if (empty($d['r'])) {
}

Psalm output (using commit 0ffb833):

ERROR: TypeDoesNotContainType - 8:5 - Found a contradiction when evaluating $d['r'] and trying to reconcile type 'string(a)' to empty