我得到以下错误，但它说，在Magento核心。我想知道如何调试这个，因为我相信没有什么错在Magentos核心。
下面是错误：

30-Apr-2018 18:05:23 UTC] PHP Fatal error:  Uncaught Error: Call to a member function getMetaTitle() on null in /home/example/public_html/app/code/core/Mage/Catalog/Block/Product/View.php:18
Stack trace:
#0 /home/example/public_html/app/code/core/Mage/Core/Block/Abstract.php(139): Mage_Catalog_Block_Product_View->_prepareLayout()
#1 /home/example/public_html/app/code/core/Mage/Core/Model/Layout.php(322): Mage_Core_Block_Abstract->setLayout(Object(Inchoo_PHP7_Model_Layout))
#2 /home/example/public_html/app/code/core/Mage/Core/Model/Layout.php(332): Mage_Core_Model_Layout->createBlock('review/product_...', 'product.info')
#3 /home/example/public_html/app/code/core/Mage/Core/Model/Layout.php(147): Mage_Core_Model_Layout->addBlock('review/product_...', 'product.info')
#4 /home/example/public_html/app/code/core/Mage/Core/Model/Layout.php(119): Mage_Core_Model_Layout->_generateBlock(Object(Mage_Core_Model_Layout_Element), Object(Mage_Core_Model_Layout_Element))
#5 /home/example/public_html/app/co in /home/example/public_html/app/code/core/Mage/Catalog/Block/Product/View.php on line 18

/home/angelsforeveryon/public_html/app/code/core/Mage/Catalog/Block/Product/View.php:18

protected function _prepareLayout()
{
    $this->getLayout()->createBlock('catalog/breadcrumbs');
    $headBlock = $this->getLayout()->getBlock('head');
    if ($headBlock) {
        $product = $this->getProduct();
  line 18 here -->     $title = $product->getMetaTitle();
        if ($title) {
            $headBlock->setTitle($title);
        }
        $keyword = $product->getMetaKeyword();
        $currentCategory = Mage::registry('current_category');
        if ($keyword) {
            $headBlock->setKeywords($keyword);
        } elseif ($currentCategory) {
            $headBlock->setKeywords($product->getName());
        }
        $description = $product->getMetaDescription();
        if ($description) {
            $headBlock->setDescription( ($description) );
        } else {
            $headBlock->setDescription(Mage::helper('core/string')->substr($product->getDescription(), 0, 255));
        }
        if ($this->helper('catalog/product')->canUseCanonicalTag()) {
            $params = array('_ignore_category' => true);
            $headBlock->addLinkRel('canonical', $product->getUrlModel()->getUrl($product, $params));
        }
    }

    return parent::_prepareLayout();
}