Why am I seeing "Undefined index: und" when I'm using LANGUAGE_NONE? I've never seen this before, I'm getting an


  Undefined index: und in mymodule_page_alter...


on a line where I'm checking this

$node-&gt;field_override_ads[LANGUAGE_NONE][0]['value'] == 0


Is this a bug, or am I missing something?
if(count($node-&gt;field_override_ads) &amp;&amp; $node-&gt;field_override_ads[LANGUAGE_NONE][0]['value'] == 0)


You need to check if a value even exists before checking the value. And I'd actually write it this way:

if(count($node-&gt;field_override_ads) &amp;&amp; !$node-&gt;field_override_ads[LANGUAGE_NONE][0]['value'])