Magento – Magento 2 : Fatal error: Uncaught Error: Call to a member function dispatch()

Replace below code with your block code

namespace Lapisbard\General\Block;
use Magento\Customer\Model\Session;

class CustomerAccount extends \Magento\Framework\View\Element\Template {
    public function __construct(\Magento\Framework\View\Element\Template\Context $context,
        Session $customerSession
    )
    {
        parent::__construct($context);
        $this->_customerSession = $customerSession;
    }
    public function isCustomerLoggedIn() {
        return $this->_customerSession->isLoggedIn();
    }
}

Then you can use it

echo $this->getLayout()->createBlock("Lapisbard\General\Block\CustomerAccount")->setTemplate("Lapisbard_General::customer_account.phtml")->toHtml();

The problem is that your constructor does not match the parent class constructor.

To fix that you need to update your constructor:

public function __construct(
    \Magento\Framework\View\Element\Template\Context $context,
    \Magento\Customer\Model\Session $customerSession,  
    \Magento\Framework\ObjectManagerInterface $objectManager,
    array $data = []
 ) {
    parent::__construct($context, $data);
    $this->customerSession = $customerSession;
    $this->_objectManager = $objectManager;
  }

Don't forget to flush the var/cache and var/generation after your changes.