Avoid breaking import when fetching fail

graby will throw an Exception in some case (like a bad url, a restricted url or a secured pdf).

Import doesn't handle that case and break the whole import.
With that commit the import isn't stopped but the entry is just skipped.

Also, as a  bonus, I've added extra test on WallabagImportV2 when the json is empty.

src/Wallabag/ImportBundle/Import/AbstractImport.php

@@ -0,0 +1,47 @@
+<?php
+
+namespace Wallabag\ImportBundle\Import;
+
+use Psr\Log\LoggerInterface;
+use Psr\Log\NullLogger;
+use Doctrine\ORM\EntityManager;
+use Wallabag\CoreBundle\Helper\ContentProxy;
+use Wallabag\CoreBundle\Entity\Entry;
+
+abstract class AbstractImport implements ImportInterface
+{
+    protected $em;
+    protected $logger;
+    protected $contentProxy;
+
+    public function __construct(EntityManager $em, ContentProxy $contentProxy)
+    {
+        $this->em = $em;
+        $this->logger = new NullLogger();
+        $this->contentProxy = $contentProxy;
+    }
+
+    public function setLogger(LoggerInterface $logger)
+    {
+        $this->logger = $logger;
+    }
+
+    /**
+     * Fetch content from the ContentProxy (using graby).
+     * If it fails return false instead of the updated entry.
+     *
+     * @param Entry  $entry   Entry to update
+     * @param string $url     Url to grab content for
+     * @param array  $content An array with AT LEAST keys title, html, url, language & content_type to skip the fetchContent from the url
+     *
+     * @return Entry|false
+     */
+    protected function fetchContent(Entry $entry, $url, array $content = [])
+    {
+        try {
+            return $this->contentProxy->updateEntry($entry, $url, $content);
+        } catch (\Exception $e) {
+            return false;
+        }
+    }
+}