Fix more notices.

plugins/FeedsHTTPFetcher.inc

@@ -131,7 +131,7 @@ class FeedsHTTPFetcher extends FeedsFetcher {
         FEEDS_HTTP_BASIC_AUTH_PER_SOURCE => t('Specify credentials when creating a feed.'),
         FEEDS_HTTP_BASIC_AUTH_PER_IMPORTER => t('One set of credentials for all feeds.'),
       ),
-      '#default_value' => $this->config['basic_auth'],
+      '#default_value' => isset($this->config['basic_auth']) ? $this->config['basic_auth'] : FEEDS_HTTP_NO_BASIC_AUTH,
     );
     $form['basic_auth'] += $this->basicAuthForm($this->config);
     return $form;