Joomla 2.5 + Takai template
Nginx error log:
[error] 3215#0: *3323 FastCGI sent in stderr: "PHP message: PHP Notice: Undefined property: JDocumentError::$params in templates/takai/includes/helper.php on line 92

PHP message: PHP Fatal error: Call to a member function get() on a non-object in /www/templates/takai/includes/helper.php on line 92" while reading response header from upstream,

what wrong with helper.php on line 92?

This line reads the parameters ($params) from the template details.xml file.

Are you using the latest version of the template (1.0.2)?
Did you use the quickstart package?

Finally I think you should try reinstalling the template.