I found a similar bug.
Notice: Undefined index: aiosp_front_meta_tags in /wp-content/plugins/all-in-one-seo-pack/aioseop.class.php on line 2382
The fix could be to change line 346 from this:
$front_meta = stripcslashes($aioseop_options['aiosp_front_meta_tags']);
$front_meta = isset($aioseop_options['aiosp_front_meta_tags']) ? '' : stripcslashes($aioseop_options['aiosp_front_meta_tags']);
The frustrating part about this particular bug is that the error notice HTML code got printed into the "Additional Front Page Headers:" textarea on the options page. Normally, this HTML would render as a big, ugly, orange-headed table, but since it was wrapped in the textarea tags, it rendered as an inconspicuous block of editable plain text. So when I updated the options, I didn't notice that this textarea field had been populated with the error notice's raw HTML, and I essentially saved the error notice HTML as an "Additional Front Page Header". Then when I viewed the home page, I saw the big orange error notice--despite the fact that PHP loaded the page without any errors. The error notice code was simply being retrieved from
$aioseop_options['aiosp_front_meta_tags'] and inserted into the head section.