We're sorry for the trouble. This isn't a warning we've seen before, but it's a silly mistake on our part that's easily correctible.
To fix, please edit the components/com_jfbconnect/libraries/provider/pinterest/widget/share.php file. Around line 106, you'll see the following line:
return '//assets.pinterest.com/images/pidgets/'+$image+'.png';
Change those plus signs (+) to periods (.) like:
return '//assets.pinterest.com/images/pidgets/' . $image . '.png';
Also, do the same thing on line 103 by changing:
$image = 'pinit_fg_en_rect_'+$color+'_'+$num;
to:
$image = 'pinit_fg_en_rect_' . $color . '_' . $num;
I hope that helps, but should you need anything else, just let us know.
Thanks,
Alex