docs: improve explanation

Author: kenjis

user_guide_src/source/libraries/curlrequest.rst

@@ -272,8 +272,11 @@ further headers arrays or calls to ``setHeader()``.
 http_errors
 ===========
 
-By default, CURLRequest will fail if the HTTP code returned is greater than or equal to 400. You can set
-``http_errors`` to ``false`` to return the content instead:
+By default, CURLRequest will throw ``HTTPException`` if the HTTP code returned is
+greater than or equal to 400.
+
+If you want to see the response body, you can set ``http_errors`` to ``false`` to
+return the content instead:
 
 .. literalinclude:: curlrequest/026.php
 

user_guide_src/source/libraries/curlrequest/026.php

@@ -1,8 +1,9 @@
 <?php
 
 $client->request('GET', '/status/500');
-// Will fail verbosely
+// If the response code is 500, an HTTPException is thrown,
+// and a detailed error report is displayed if in development mode.
 
-$res = $client->request('GET', '/status/500', ['http_errors' => false]);
-echo $res->getStatusCode();
-// 500
+$response = $client->request('GET', '/status/500', ['http_errors' => false]);
+echo $response->getStatusCode(); // 500
+echo $response->getBody();       // You can see the response body.