Hey ragtech,
That message is related to the Facebook “Like Box” widget we include in the plugin. It’s not actually an error, but just a notice that appears in the browser console and won’t affect the functionality of the plugin at all. The only way to remove it is to set up a Facebook App on their developer site, enter your website URL into the App settings, and then enter the ID of that App into the “App ID” field on our plugin’s Misc settings tab. As this is a lot of work for every user to do then we don’t ask them to do this as it isn’t required, but if you’d like to remove that notice from the browser console then I can give you more detailed directions on how to do that. Alternatively, you could just disable the Like Box by using the following setting: Facebook Feed > Customize > Misc > Like Box > Show Like Box
Let me know whether that makes sense, or if you have any other questions at all.
John