I found the same issue today.
Don’t know why it suddenly happened, but I know what causes the warnings.
In kickstarter-tracker-widget.php the calls to curl_errno and curl_error are called after curl_close(), which means they try to connect to an invalid curl stream.
My solution was to move curl_close($ch); from line 45 to line 52, just after the if (!$html) { } block.
Hopefully this will get fixed in an update?
