Magento 2.1 – Fix Image Not Uploading in Edit Form

I am working on magento 2.1 form. Image is uploaded successfully when i add new field. however when i edit any field from grid then file uploader will not shown on page.
When i inspect edit page it shows following error

Uncaught TypeError: value.map is not a function in
file-uploader.js:69

<field name="image">
        <argument name="data" xsi:type="array">
            <item name="config" xsi:type="array">
                <item name="dataType" xsi:type="string">string</item>
                <item name="source" xsi:type="string">faqs</item>
                <item name="label" xsi:type="string" translate="true">Topic Image</item>
                <item name="visible" xsi:type="boolean">true</item>
                <item name="formElement" xsi:type="string">fileUploader</item>
                <item name="elementTmpl" xsi:type="string">ui/form/element/uploader/uploader</item> 
               <item name="previewTmpl" xsi:type="string">Magento_Catalog/image-preview</item> 
               <item name="dataScope" xsi:type="string">image</item>
                <item name="required" xsi:type="boolean">false</item>
                <item name="sortOrder" xsi:type="number">13</item>
                <item name="uploaderConfig" xsi:type="array">
                    <item name="url" xsi:type="url" path="faqs/topic_image/upload"/>
                </item>
            </item>
        </argument>
    </field>

In \app\code\Spacename\Moduelname\etc\di.xml

<type name="Spacename\modulename\Controller\Adminhtml\Topic\Image\Upload">
<arguments>
    <argument name="imageUploader" xsi:type="object">Magento\Catalog\CategoryImageUpload</argument>
</arguments>
</type>


<virtualType name="Magento\Catalog\CategoryImageUpload" type="spacename\modulename\Model\ImageUploader">
<arguments>
    <argument name="baseTmpPath" xsi:type="string">faqs</argument>
    <argument name="basePath" xsi:type="string">faqs</argument>
    <argument name="allowedExtensions" xsi:type="array">
        <item name="jpg" xsi:type="string">jpg</item>
        <item name="jpeg" xsi:type="string">jpeg</item>
        <item name="gif" xsi:type="string">gif</item>
        <item name="png" xsi:type="string">png</item>
    </argument>
</arguments>

In controller app\code\Spacename\Moduelname\Controller\Adminhtml\Topic\Image upload.php

    class Upload extends \Magento\Backend\App\Action
{
    /**
     * Image uploader
     *
     * @var \Magento\Catalog\Model\ImageUploader
     */
    protected $baseTmpPath;
    protected $imageUploader;

    /**
     * Upload constructor.
     *
     * @param \Magento\Backend\App\Action\Context $context
     * @param \Magento\Catalog\Model\ImageUploader $imageUploader
     */
    public function __construct(
        \Magento\Backend\App\Action\Context $context,
        \spacename\modulename\Model\ImageUploader $imageUploader
    ) {
        parent::__construct($context);
        $this->imageUploader = $imageUploader;
    }

    /**
     * Check admin permissions for this controller
     *
     * @return boolean
     */
    protected function _isAllowed()
    {
        return $this->_authorization->isAllowed('spacename_Modulename::entity');
    }

    /**
     * Upload file controller action
     *
     * @return \Magento\Framework\Controller\ResultInterface
     */
    public function execute()
    {

        try {
            $result = $this->imageUploader->saveFileToTmpDir('image');

            $result['cookie'] = [
                'name' => $this->_getSession()->getName(),
                'value' => $this->_getSession()->getSessionId(),
                'lifetime' => $this->_getSession()->getCookieLifetime(),
                'path' => $this->_getSession()->getCookiePath(),
                'domain' => $this->_getSession()->getCookieDomain(),
            ];
        } catch (\Exception $e) {
            $result = ['error' => $e->getMessage(), 'errorcode' => $e->getCode()];
        }
        return $this->resultFactory->create(ResultFactory::TYPE_JSON)->setData($result);
    }
}

and in model \code\Spacename\Moduelname\Model\ImageUploader.php

    <?php
/**
 * Copyright © 2016 Magento. All rights reserved.
 * See COPYING.txt for license details.
 */
namespace spacename\modulename\Model;

/**
 * Catalog image uploader
 */
class ImageUploader
{
    /**
     * Core file storage database
     *
     * @var \Magento\MediaStorage\Helper\File\Storage\Database
     */
    protected $coreFileStorageDatabase;

    /**
     * Media directory object (writable).
     *
     * @var \Magento\Framework\Filesystem\Directory\WriteInterface
     */
    protected $mediaDirectory;

    /**
     * Uploader factory
     *
     * @var \Magento\MediaStorage\Model\File\UploaderFactory
     */
    private $uploaderFactory;

    /**
     * Store manager
     *
     * @var \Magento\Store\Model\StoreManagerInterface
     */
    protected $storeManager;

    /**
     * @var \Psr\Log\LoggerInterface
     */
    protected $logger;

    /**
     * Base tmp path
     *
     * @var string
     */
    protected $baseTmpPath;

    /**
     * Base path
     *
     * @var string
     */
    protected $basePath;

    /**
     * Allowed extensions
     *
     * @var string
     */
    protected $allowedExtensions;

    /**
     * ImageUploader constructor
     *
     * @param \Magento\MediaStorage\Helper\File\Storage\Database $coreFileStorageDatabase
     * @param \Magento\Framework\Filesystem $filesystem
     * @param \Magento\MediaStorage\Model\File\UploaderFactory $uploaderFactory
     * @param \Magento\Store\Model\StoreManagerInterface $storeManager
     * @param \Psr\Log\LoggerInterface $logger
     * @param string $baseTmpPath
     * @param string $basePath
     * @param string[] $allowedExtensions
     */
    public function __construct(
        \Magento\MediaStorage\Helper\File\Storage\Database $coreFileStorageDatabase,
        \Magento\Framework\Filesystem $filesystem,
        \Magento\MediaStorage\Model\File\UploaderFactory $uploaderFactory,
        \Magento\Store\Model\StoreManagerInterface $storeManager,
        \Psr\Log\LoggerInterface $logger,
        $baseTmpPath,
        $basePath,
        $allowedExtensions
    ) {
        $this->coreFileStorageDatabase = $coreFileStorageDatabase;
        $this->mediaDirectory = $filesystem->getDirectoryWrite(\Magento\Framework\App\Filesystem\DirectoryList::MEDIA);
        $this->uploaderFactory = $uploaderFactory;
        $this->storeManager = $storeManager;
        $this->logger = $logger;
        $this->baseTmpPath = $baseTmpPath;
        $this->basePath = $basePath;
        $this->allowedExtensions = $allowedExtensions;
    }

    /**
     * Set base tmp path
     *
     * @param string $baseTmpPath
     *
     * @return void
     */
    public function setBaseTmpPath($baseTmpPath)
    {
        $this->baseTmpPath = $baseTmpPath;
    }

    /**
     * Set base path
     *
     * @param string $basePath
     *
     * @return void
     */
    public function setBasePath($basePath)
    {
        $this->basePath = $basePath;
    }

    /**
     * Set allowed extensions
     *
     * @param string[] $allowedExtensions
     *
     * @return void
     */
    public function setAllowedExtensions($allowedExtensions)
    {
        $this->allowedExtensions = $allowedExtensions;
    }

    /**
     * Retrieve base tmp path
     *
     * @return string
     */
    public function getBaseTmpPath()
    {

        return $this->baseTmpPath;
    }

    /**
     * Retrieve base path
     *
     * @return string
     */
    public function getBasePath()
    {
        return $this->basePath;
    }

    /**
     * Retrieve base path
     *
     * @return string[]
     */
    public function getAllowedExtensions()
    {
        return $this->allowedExtensions;
    }

    /**
     * Retrieve path
     *
     * @param string $path
     * @param string $imageName
     *
     * @return string
     */
    public function getFilePath($path, $imageName)
    {
        return rtrim($path, '/') . '/' . ltrim($imageName, '/');
    }

    /**
     * Checking file for moving and move it
     *
     * @param string $imageName
     *
     * @return string
     *
     * @throws \Magento\Framework\Exception\LocalizedException
     */
    public function moveFileFromTmp($imageName)
    {
        $baseTmpPath = $this->getBaseTmpPath();
        $basePath = $this->getBasePath();


        $baseImagePath = $this->getFilePath($basePath, $imageName);
        $baseTmpImagePath = $this->getFilePath($baseTmpPath, $imageName);

        try {
            $this->coreFileStorageDatabase->copyFile(
                $baseTmpImagePath,
                $baseImagePath
            );
            $this->mediaDirectory->renameFile(
                $baseTmpImagePath,
                $baseImagePath
            );
        } catch (\Exception $e) {
            throw new \Magento\Framework\Exception\LocalizedException(
                __('Something went wrong while saving the file(s).')
            );
        }

        return $imageName;
    }

    /**
     * Checking file for save and save it to tmp dir
     *
     * @param string $fileId
     *
     * @return string[]
     *
     * @throws \Magento\Framework\Exception\LocalizedException
     */
    public function saveFileToTmpDir($fileId)
    {
        $baseTmpPath = $this->getBaseTmpPath();

        $uploader = $this->uploaderFactory->create(['fileId' => $fileId]);
        $uploader->setAllowedExtensions($this->getAllowedExtensions());
        $uploader->setAllowRenameFiles(true);

        $result = $uploader->save($this->mediaDirectory->getAbsolutePath($baseTmpPath));

        if (!$result) {
            throw new \Magento\Framework\Exception\LocalizedException(
                __('File can not be saved to the destination folder.')
            );
        }

        /**
         * Workaround for prototype 1.7 methods "isJSON", "evalJSON" on Windows OS
         */
        $result['tmp_name'] = str_replace('\\', '/', $result['tmp_name']);
        $result['path'] = str_replace('\\', '/', $result['path']);
        $result['url'] = $this->storeManager
                ->getStore()
                ->getBaseUrl(
                    \Magento\Framework\UrlInterface::URL_TYPE_MEDIA
                ) . $this->getFilePath($baseTmpPath, $result['file']);
        $result['name'] = $result['file'];

        if (isset($result['file'])) {
            try {
                $relativePath = rtrim($baseTmpPath, '/') . '/' . ltrim($result['file'], '/');
                $this->coreFileStorageDatabase->saveFile($relativePath);
            } catch (\Exception $e) {
                $this->logger->critical($e);
                throw new \Magento\Framework\Exception\LocalizedException(
                    __('Something went wrong while saving the file(s).')
                );
            }
        }

        return $result;
    }
}