Fatal error: Uncaught Error: Call to a member function isAdmin() on string in /var/www/vhosts/h-tune.co.uk/site/magento/app/code/core/Mage/Core/Model/Design/Package.php:847 Stack trace: #0 /var/www/vhosts/h-tune.co.uk/site/magento/app/code/core/Mage/Core/Model/Design/Package.php(825): Mage_Core_Model_Design_Package->_prepareUrl('../images/amsho...') #1 [internal function]: Mage_Core_Model_Design_Package->_cssMergerUrlCallback(Array) #2 /var/www/vhosts/h-tune.co.uk/site/magento/app/code/core/Mage/Core/Model/Design/Package.php(785): preg_replace_callback('/url\\(\\s*(?!dat...', Array, '.block-layered-...') #3 /var/www/vhosts/h-tune.co.uk/site/magento/app/code/community/Mandagreen/Minifier/Core/Model/Design/Package.php(82): Mage_Core_Model_Design_Package->beforeMergeCss('/var/www/vhosts...', '.block-layered-...') #4 /var/www/vhosts/h-tune.co.uk/site/magento/app/code/core/Mage/Core/Helper/Data.php(744): Mandagreen_Minifier_Core_Model_Design_Package->beforeMergeCss('/var/www/vhosts...', '.block-layered-...') #5 /var/www/vhosts in /var/www/vhosts/h-tune.co.uk/site/magento/app/code/core/Mage/Core/Model/Design/Package.php on line 847