Magento 2 – Issue Adding Custom Top Links in Header

Suppose package:Learning and module: Custom

Module.xml looks like

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../../lib/internal/Magento/Framework/Module/etc/module.xsd">
    <module name="Learning_Custom" setup_version="2.0.0">
        <sequence>
            <module name="Magento_Catalog"/>
        </sequence>
    </module>
</config>

And then create a layout xml following path -> app/code/Learning/Custom/view/frontend/layout/catalog_product_prices.xml

<layout xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../../../../lib/internal/Magento/Framework/View/Layout/etc/layout_generic.xsd">
    <referenceBlock name="render.product.prices">
        <arguments>
            <argument name="default" xsi:type="array">
                <item name="prices" xsi:type="array">
                    <item name="tier_price" xsi:type="array">
                        <item name="render_template" xsi:type="string">Learning_Custom::product/price/tier_prices.phtml
                    </item>
                </item>
            </argument>
        </arguments>
    </referenceBlock>
</layout>

Create template inside your module or copy base template file inside your module path should be -> app/code/Learning/Custom/view/frontend/templates/product/price/tier_prices.phtml

Create a new class called Wundercarparts\Makeanoffer\Model\ResourceModel\Offers\Grid\Collection (place it in the proper file to match the file path).

The class should look like this

<?php
namespace Wundercarparts\Makeanoffer\Model\ResourceModel\Offers\Grid;

use Magento\Framework\Api\SearchCriteriaInterface;
use Magento\Framework\Api\Search\SearchResultInterface;
use Magento\Framework\DB\Adapter\AdapterInterface;
use Magento\Framework\Data\Collection\Db\FetchStrategyInterface;
use Magento\Framework\Data\Collection\EntityFactoryInterface;
use Magento\Framework\Event\ManagerInterface as EventManagerInterface;
use Magento\Framework\Model\ResourceModel\Db\AbstractDb;
use Magento\Framework\Api\Search\AggregationInterface;
use Psr\Log\LoggerInterface;
use Wundercarparts\Makeanoffer\Model\ResourceModel\Offers\Collection as OffersCollection;

class Collection extends OffersCollection implements SearchResultInterface
{
    /**
     * Aggregations
     * 
     * @var AggregationInterface
     */
    protected $aggregations;

    /**
     * constructor
     * 
     * @param EntityFactoryInterface $entityFactory
     * @param LoggerInterface $logger
     * @param FetchStrategyInterface $fetchStrategy
     * @param EventManagerInterface $eventManager
     * @param string $mainTable
     * @param string $eventPrefix
     * @param string $eventObject
     * @param string $resourceModel
     * @param AdapterInterface $connection
     * @param AbstractDb $resource
     * @param $model
     */
    public function __construct(
        EntityFactoryInterface $entityFactory,
        LoggerInterface $logger,
        FetchStrategyInterface $fetchStrategy,
        EventManagerInterface $eventManager,
        $mainTable,
        $eventPrefix,
        $eventObject,
        $resourceModel,
        AdapterInterface $connection = null,
        AbstractDb $resource = null,
        $model = 'Magento\Framework\View\Element\UiComponent\DataProvider\Document'
    )
    {
        parent::__construct($entityFactory, $logger, $fetchStrategy, $eventManager, $connection, $resource);
        $this->_eventPrefix = $eventPrefix;
        $this->_eventObject = $eventObject;
        $this->_init($model, $resourceModel);
        $this->setMainTable($mainTable);
    }


    /**
     * @return AggregationInterface
     */
    public function getAggregations()
    {
        return $this->aggregations;
    }

    /**
     * @param AggregationInterface $aggregations
     * @return $this
     */
    public function setAggregations($aggregations)
    {
        $this->aggregations = $aggregations;
    }


    /**
     * Retrieve all ids for collection
     * Backward compatibility with EAV collection
     *
     * @param int $limit
     * @param int $offset
     * @return array
     */
    public function getAllIds($limit = null, $offset = null)
    {
        return $this->getConnection()->fetchCol($this->_getAllIdsSelect($limit, $offset), $this->_bindParams);
    }

    /**
     * Get search criteria.
     *
     * @return \Magento\Framework\Api\SearchCriteriaInterface|null
     */
    public function getSearchCriteria()
    {
        return null;
    }

    /**
     * Set search criteria.
     *
     * @param SearchCriteriaInterface $searchCriteria
     * @return $this
     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
     */
    public function setSearchCriteria(SearchCriteriaInterface $searchCriteria = null)
    {
        return $this;
    }

    /**
     * Get total count.
     *
     * @return int
     */
    public function getTotalCount()
    {
        return $this->getSize();
    }

    /**
     * Set total count.
     *
     * @param int $totalCount
     * @return $this
     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
     */
    public function setTotalCount($totalCount)
    {
        return $this;
    }

    /**
     * Set items list.
     *
     * @param \Magento\Framework\Api\ExtensibleDataInterface[] $items
     * @return $this
     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
     */
    public function setItems(array $items = null)
    {
        return $this;
    }
}

then replace in di.xml this

<item name="offers_ui_listing_data_source" xsi:type="string">Wundercarparts\Makeanoffer\Model\ResourceModel\Offers\Collection</item>

with this

<item name="offers_ui_listing_data_source" xsi:type="string">Wundercarparts\Makeanoffer\Model\ResourceModel\Offers\Grid\Collection</item>

and this line

<type name="Wundercarparts\Makeanoffer\Model\ResourceModel\Offers\Collection"> 

with

<type name="Wundercarparts\Makeanoffer\Model\ResourceModel\Offers\Grid\Collection">

For this last line, if your Offers collection expects the parameters mainTable and others, instead of changing the line, duplicate the section that starts with <type name="Wundercarparts\Makeanoffer\Model\ResourceModel\Offers\Collection"> and then replace the line for the one you just cloned.