i got an issue in checkout page like Uncaught Error: Call to a member function getFee() on null

[ramsampathi]

I am using onestepcheckout module in my site and we go a error like
Fatal error: Uncaught Error: Call to a member function getFee() on null in Sivajik34/CustomFee/Plugin/Checkout/Model/ShippingInformationManagement.php:41 Stack trace: #0 /home/devserve/public_html/hookandloop99/vendor/magento/framework/Interception/Interceptor.php(121): Sivajik34\CustomFee\Plugin\Checkout\Model\ShippingInformationManagement->beforeSaveAddressInformation(Object(Magento\Checkout\Model\ShippingInformationManagement\Interceptor), '111', Object(Magento\Checkout\Model\ShippingInformation)) #1 /home/devserve/public_html/hookandloop99/vendor/magento/framework/Interception/Interceptor.php(153): Magento\Checkout\Model\ShippingInformationManagement\Interceptor->Magento\Framework\Interception{closure}('111', Object(Magento\Checkout\Model\ShippingInformation)) #2 /generated/code/Magento/Checkout/Model/ShippingInformationManagement/Interceptor.php(26): Magento\Checkout\Model\ShippingInformationManagement\Interceptor->___callPlugi in Sivajik34/CustomFee/Plugin/Checkout/Model/ShippingInformationManagement.php on line 41

Any solution is there?