Question about "undefined index" error

The file name and line number will always be accurate because they’re reported directly by PHP. It sounds like the component isn’t being identified correctly.

Is it a public plugin? Can you let me know which one if so? Or link me to some code if not?

Yes, the plugin is Posts in Sidebar. Thanks for looking into it!

I’ve fixed the underlying issue here by the way. The fix will be included in the next version of Query Monitor.

Fixed in 2.6.8.

Thank you!