diff --git a/lib/_config.php b/lib/_config.php
index 5d63b1d..d839edd 100644
--- a/lib/_config.php
+++ b/lib/_config.php
@@ -4,7 +4,7 @@
 
 define('PRESTO', 'presto.php');
 define('PRESTO_VERSION', 'presto-v1.11');
-define('PRESTO_DEBUG', 0);
+define('PRESTO_DEBUG', 1);
 define('PRESTO_TRACE', 1);
 define('PRESTO_TRACE_KEY', '_presto_trace');
 define('VERSION_HEADER', 'X-Api-Version');
@@ -51,6 +51,10 @@ public static function errorHandlerCallback($code, $string, $file, $line, $conte
 // Set up PHP error handling (note these settings are overriden by explicit PHP ini settigns, we should address this)
 
 assert_options(ASSERT_WARNING, 0);
+if (PRESTO_DEBUG) {
+	assert_options(ASSERT_ACTIVE, 1);
+	assert_options(ASSERT_WARNING, 1);
+}
 ini_set('html_errors', false);
 error_reporting(E_ALL);
 set_error_handler(array("PrestoException", "errorHandlerCallback"), E_ALL);
diff --git a/lib/api.php b/lib/api.php
index 19023e0..b160f96 100644
--- a/lib/api.php
+++ b/lib/api.php
@@ -53,9 +53,9 @@ public function restrictTo($types) {
 
 	*/
 	public function crossOrigin() {
-	
+
 		if (empty($_SERVER['HTTP_ORIGIN']))
-			throw new Exception("'HTTP_ORIGIN' unknown. Failed to set required 'Access-Control-Allow-Origin' header for CORS handshake.", 500);
+			return; // This is not a CORS request
 			
 		$this->add_header('Access-Control-Allow-Origin', $_SERVER['HTTP_ORIGIN']);
 		$this->add_header('Access-Control-Allow-Credentials', 'true');