RemoteFetcherWorker: Make sure {:error, _} is returned on failure

Otherwise jobs are considered a success.

lib/pleroma/workers/remote_fetcher_worker.ex

@@ -22,8 +22,11 @@ def perform(%Job{args: %{"op" => "fetch_remote", "id" => id} = args}) do
       {:error, :allowed_depth} ->
         {:discard, :allowed_depth}
 
-      _ ->
+      {:error, _} = e ->
-        :error
+        e
+
+      e ->
+        {:error, e}
     end
   end