Checking if list object property is empty does not convert to non-empty-list

[M393]

~https://psalm.dev/r/d375837035~

[psalm-github-bot[bot]]

I found these snippets:

https://psalm.dev/r/d375837035

```php $l * @return non-empty-list|null */ function f(array $l): array { if ($l === []) { return null; } return $l; } ``` ``` Psalm output (using commit d4c5f85): ERROR: MismatchingDocblockReturnType - 5:12 - Docblock has incorrect return type 'non-empty-list|null', should be 'array' INFO: MixedInferredReturnType - 5:12 - Could not verify return type 'non-empty-list|null' for f ```

[M393]

https://psalm.dev/r/4a67e451d8

[psalm-github-bot[bot]]

I found these snippets:

https://psalm.dev/r/4a67e451d8

```php } $o * @return non-empty-list|null */ function f(object $o): ?array { if ($o->l === []) { return null; } /** @psalm-trace $o $o->l*/ return $o->l; } ``` ``` Psalm output (using commit d4c5f85): INFO: MixedReturnStatement - 12:12 - Could not infer a return type INFO: Trace - 12:5 - $o: object{l:list} INFO: Trace - 12:5 - $o->l: mixed INFO: MixedInferredReturnType - 5:12 - Could not verify return type 'non-empty-list|null' for f ```