[CodeQuality] Skip empty cases on SwitchTrueToIfRector

[samsonasik]

Per #3535 (comment), if empty cases not skipped, it will got error:

There was 1 error:

1) Rector\Tests\CodeQuality\Rector\Switch_\SwitchTrueToIfRector\SwitchTrueToIfRectorTest::test with data set #1
Rector\Core\Exception\ShouldNotHappenException: Array of nodes cannot be empty. Ensure "Rector\CodeQuality\Rector\Switch_\SwitchTrueToIfRector->refactor()" returns non-empty array for Nodes.

A) Return null for no change:

    return null;

B) Remove the Node:

    $this->removeNode($node);
    return $node;

[samsonasik]

@TomasVotruba it fixed 🎉

[TomasVotruba]

Thanks 🥳