Do not error on NotFoundException

Since this exception can be thrown when a shared file is in the
trashbin there is no need to spam the log like crazy.

Fixes #938

apps/files_sharing/lib/sharedstorage.php

@@ -36,6 +36,7 @@
 use OCA\Files_Sharing\ISharedStorage;
 use OCP\Constants;
 use OCP\Files\Cache\ICacheEntry;
+use OCP\Files\NotFoundException;
 use OCP\Files\Storage\IStorage;
 use OCP\Lock\ILockingProvider;
 
@@ -94,6 +95,9 @@ private function init() {
 			$sourcePath = $this->ownerView->getPath($this->superShare->getNodeId());
 			list($this->storage, $this->rootPath) = $this->ownerView->resolvePath($sourcePath);
 			$this->sourceRootInfo = $this->storage->getCache()->get($this->rootPath);
+		} catch (NotFoundException $e) {
+			$this->storage = new FailedStorage(['exception' => $e]);
+			$this->rootPath = '';
 		} catch (\Exception $e) {
 			$this->storage = new FailedStorage(['exception' => $e]);
 			$this->rootPath = '';