修复请求失败时可能导致的调试信息出错的问题

src/base/Client.php

@@ -245,7 +245,7 @@ class Client
 				$info .= "\r\n=====ERROR=====\r\nErrorNo: $errno\r\nErrorMsg: $errmsg\r\n";
 			}
 
-			$info .= "\r\n=====REQUEST=====\r\n{$httpInfo['request_header']}";
+			$info .= "\r\n=====REQUEST=====\r\n".isset($httpInfo['request_header']) ? $httpInfo['request_header'] : "**Reqeust Failed**\r\n";
 
 			if (isset($body)) {
 				$info .= $body."\r\n";