Correct error output of getCategoryFeeds

lib/REST/Miniflux/V1.php

@@ -689,7 +689,7 @@ class V1 extends \JKingWeb\Arsse\REST\AbstractHandler {
             $subs = Arsse::$db->subscriptionList(Arsse::$user->id, $folder, $recursive)->getAll();
         } catch (ExceptionInput $e) {
             // the folder does not exist
-            return new EmptyResponse(404);
+            return new ErrorResponse("404", 404);
         }
         // compile the list of folders; the feed list includes folder names
         // NOTE: We compile the full list of folders in case someone has manually selected a non-top folder

tests/cases/REST/Miniflux/TestV1.php

@@ -575,7 +575,7 @@ class TestV1 extends \JKingWeb\Arsse\Test\AbstractTest {
 
     public function testListFeedsOfAMissingCategory(): void {
         \Phake::when(Arsse::$db)->subscriptionList->thenThrow(new ExceptionInput("idMissing"));
-        $exp = new EmptyResponse(404);
+        $exp = new ErrorResponse("404", 404);
         $this->assertMessage($exp, $this->req("GET", "/categories/2112/feeds"));
         \Phake::verify(Arsse::$db)->subscriptionList(Arsse::$user->id, 2111, true);
     }