TYPO3 Core

Let's assume we want to use the 2nd image stored in a page's media field as a background image. We can do something like this in TypoScript to generate some inline CSS:

10 = IMG_RESOURCE
10 {
  file.import.data = levelmedia:-1, slide
  file.import.listNum = 1
  file.treatIdAsReference = 1
  stdWrap.wrap = body {background: url(|) no-repeat; background-size: cover; background-attachment: fixed;}
}

But if there is no 2nd image, a PHP warning is generated, which can flood your sys_log over time:

Core: Error handler (FE): PHP Warning: Undefined array key 1 in /typo3/sysext/frontend/Classes/ContentObject/ContentObjectRenderer.php line 2592 

The listNum() method in ContentObjectRenderer currently just blindly returns the specified/calculated index:

return $temp[$index];

I think it would be cleaner and better to do something like this (same behaviour as if the exploded content was empty):

return $temp[$index] ?? '';