Replace x() by isset(), !empty() or defaults()

- Remove extraneous parentheses around empty() calls
- Remove duplicate calls to intval(), count() or strlen() after empty()
- Replace ternary operators outputting binary value with empty() return value
- Rewrite defaults() without x()

src/Module/Feed.php

@@ -28,8 +28,8 @@ class Feed extends BaseModule
 	{
 		$a = self::getApp();
 
-		$last_update = x($_GET, 'last_update') ? $_GET['last_update'] : '';
-		$nocache     = x($_GET, 'nocache') && local_user();
+		$last_update = defaults($_GET, 'last_update', '');
+		$nocache     = !empty($_GET['nocache']) && local_user();
 
 		if ($a->argc < 2) {
 			System::httpExit(400);