Why do we need to do this using async?  I would write it as the following:

```javascript
function getCommandPaths(thisCommand) {
  assert(typeof thisCommand === 'string' && thisCommand);

  return whiltelistPaths.map(function (path) {
    if (thisCommand.startsWith('/')) {
      return thisCommand;
    } else {
      return path.join(thisPath, thisCommand);
    }
  });
}