This is just a trivial removal of unused code I stumbled upon while debugging #42361. In the original code:

$transPaths = [$path.'/translations'];
$codePaths = [$path.'/templates'];

if (!is_dir($transPaths[0]) && !isset($transPaths[1])) {
		throw new InvalidArgumentException(sprintf('"%s" is neither an enabled bundle nor a directory.', $transPaths[0]));
}

The second part of the condition isset($transPaths[1]) will always evaluate to true, since $targetPath is just set 3 lines above but only has a single element.

This check was originally to support legacy paths which was removed in b6eb1f4:

• in TranslationDebugCommand.php
• in TranslationUpdateCommand.php

Rebased from 5.3 to 5.4, see #42362
/cc @fabpot