Fatal Error for Perch Shop

Hi,

I'm currently setting up a shop and am getting a blank screen when the add to cart button is being clicked. My error log shows the following '[Mon Nov 12 15:46:07.317332 2018] [fcgid:warn] [pid 27994] [client 91.103.188.194:59738] mod_fcgid: stderr: PHP Fatal error: Call to a member function get_prices() on boolean in /home/linweb23/a/arthur.web-design.wales/user/htdocs/admin/addons/apps/perch_shop/lib/PerchShop_Cart.class.php on line 723, referer: https://arthur.web-design.wales/course.php?s=agent

Here are my diagnostics:

    Perch: 3.1.3
    Production mode: Production (100)
    Installed apps: content (3.1.3), assets (3.1.3), categories (3.1.3), perch_blog (5.6.1), perch_forms (1.12), perch_shop_orders (1.2.6), perch_shop_products (1.2.6), perch_shop (1.2.6), perch_members (1.6.4)
    DB driver: PDO
    DB tables: perch3_blog_authors (1), perch3_blog_comments (0), perch3_blog_index (25), perch3_blog_posts (1), perch3_blog_posts_to_tags (0), perch3_blog_sections (1), perch3_blog_tags (0), perch3_blog_webmention_queue (0), perch3_blogs (1), perch3_categories (0), perch3_category_counts (0), perch3_category_sets (2), perch3_content_index (189), perch3_content_items (41), perch3_content_regions (15), perch3_forms (1), perch3_forms_responses (1), perch3_menu_items (14), perch3_navigation (0), perch3_navigation_pages (0), perch3_page_templates (0), perch3_pages (7), perch3_resource_log (54), perch3_resource_tags (0), perch3_resources (14), perch3_resources_to_tags (0), perch3_settings (38), perch3_shop_addresses (0), perch3_shop_admin_index (32), perch3_shop_brands (1), perch3_shop_cart (1), perch3_shop_cart_data (1), perch3_shop_cart_items (3), perch3_shop_countries (250), perch3_shop_currencies (152), perch3_shop_customers (0), perch3_shop_emails (1), perch3_shop_index (144), perch3_shop_option_values (0), perch3_shop_options (0), perch3_shop_order_items (0), perch3_shop_order_promotions (0), perch3_shop_order_statuses (9), perch3_shop_orders (0), perch3_shop_orders_meta (1), perch3_shop_product_files (0), perch3_shop_product_option_values (0), perch3_shop_product_options (0), perch3_shop_product_tags (0), perch3_shop_products (3), perch3_shop_promotions (0), perch3_shop_sales (0), perch3_shop_search (3), perch3_shop_shipping_zone_countries (0), perch3_shop_shipping_zones (1), perch3_shop_shippings (1), perch3_shop_tax_exhibits (0), perch3_shop_tax_group_rates (1), perch3_shop_tax_groups (1), perch3_shop_tax_locations (1), perch3_shop_tax_rates (1), perch3_shop_variants (0), perch3_user_passwords (0), perch3_user_privileges (80), perch3_user_role_privileges (2), perch3_user_roles (2), perch3_users (1)
    Users: 1
    App runtimes:

    <?php
        $apps_list = [ 
            'perch_blog',
            'perch_forms',
            'perch_members',
            'perch_shop'
        ];

    Scheduled tasks for perch_blog: delete_spam_comments (1440 mins), publish_posts (1 mins), process_webmentions (1 mins)
    Editor plug-ins:
    H1: 44a5c94721e58b540b7649cf3da15f6e
    L1: f484b7bda06f1b0f78238491a7d9344e
    F1: 3b606135b33e6a102526838f4152a807
    headerColour: #ffffff
    content_singlePageEdit: 1
    helpURL:
    siteURL: /
    hideBranding: 1
    content_collapseList: 1
    lang: en-gb
    installedAt: 3.1.3
    update_3.1.3: done
    latest_version:
    on_sale_version: 3.1.3
    headerScheme: light
    perch_shop_price_tax_mode: exc
    perch_shop_site_url: https://www.dawsonstrainingwales.co.uk
    perch_shop_product_url: /shop/products/{slug}
    perch_shop_invoice_number_format: Invoice%d
    perch_blog_site_name:
    perch_blog_post_url: news-post.php?s={postSlug}
    perch_blog_slug_format: %Y-%m-%d-{postTitle}
    perch_blog_akismet_key:
    perch_blog_max_spam_days: 0
    perch_members_login_page: /members/login.php?r={returnURL}
    dashboard: 0
    sidebar_back_link: 0
    hide_pwd_reset: 0
    keyboardShortcuts: 1
    content_hideNonEditableRegions: 0
    content_frontend_edit: 0
    content_skip_region_list: 0
    assets_restrict_buckets: 0
    perch_blog_comment_notify: 0
    perch_blog_webmention_tx: 0
    perch_blog_webmention_rx: 0
    logoPath: /assets/daw-logo.png
    perch_blog_update: 5.6
    perch_shop_update: 1.2.6
    perch_shop_default_currency: 47
    perch_shop_reporting_currency: 47
    PERCH_DEVELOPMENT: 10
    PERCH_STAGING: 50
    PERCH_PRODUCTION: 100
    PERCH_DB_USERNAME: trainingdawsons
    PERCH_DB_SERVER: 213.171.200.92
    PERCH_DB_DATABASE: dawsonstraining
    PERCH_DB_PREFIX: perch3_
    PERCH_TZ: UTC
    PERCH_EMAIL_FROM: jade@picseli.co.uk
    PERCH_EMAIL_FROM_NAME: Jade Marling
    PERCH_LOGINPATH: /admin
    PERCH_PATH: /home/linweb23/a/arthur.web-design.wales/user/htdocs/admin
    PERCH_CORE: /home/linweb23/a/arthur.web-design.wales/user/htdocs/admin/core
    PERCH_RESFILEPATH: /home/linweb23/a/arthur.web-design.wales/user/htdocs/assets
    PERCH_RESPATH: /assets
    PERCH_HTML5: 1
    PERCH_RUNWAY:
    PERCH_ERROR_MODE: DIE
    PERCH_DATE_LONG: %d %B %Y
    PERCH_DATE_SHORT: %d %b %Y
    PERCH_TIME_SHORT: %H:%M
    PERCH_TIME_LONG: %H:%M:%S
    PERCH_RUNWAY_ROUTED:
    PERCH_STRONG_PASSWORDS:
    PERCH_ASSET_VERSION: 6738d5d5f5664f7c5e34
    PERCH_DEBUG:
    PERCH_PREVIEW_ARG: preview
    PERCH_TEMPLATE_PATH: /home/linweb23/a/arthur.web-design.wales/user/htdocs/admin/templates
    PERCH_TEMPLATE_FILTERS:
    PERCH_DEFAULT_DOC: index.php
    PERCH_DEFAULT_EXT: .php
    PERCH_PRODUCTION_MODE: 100
    PERCH_XHTML_MARKUP:
    PERCH_RWD: 1
    PERCH_HTML_ENTITIES:
    PERCH_SSL:
    PERCH_STRIPSLASHES:
    PERCH_PROGRESSIVE_FLUSH: 1
    PERCH_PARANOID:
    PERCH_FORCE_SECURE_COOKIES:
    PERCH_DEFAULT_BUCKET: default
    PERCH_TRANSLATION_ASSIST:
    PERCH_PASSWORD_MIN_LENGTH: 6
    PERCH_MAX_FAILED_LOGINS: 10
    PERCH_AUTH_LOCKOUT_DURATION: 1 HOUR
    PERCH_VERIFY_UPLOADS:
    PERCH_PRIV_ASSIST:
    PERCH_CUSTOM_EDITOR_CONFIGS:
    PERCH_ENABLE_EXIF: 1
    PERCH_AUTH_PLUGIN:
    PERCH_DB_CHARSET: utf8
    PERCH_DB_PORT:
    PERCH_DB_SOCKET:
    PERCH_SHOP_VERSION: 1.2.6
    PERCH_APPS_EDITOR_PLUGIN: markitup
    PERCH_APPS_EDITOR_MARKUP_LANGUAGE: markdown

Hosting settings

    PHP: 5.6.38
    Zend: 2.6.0
    OS: Linux
    SAPI: cgi-fcgi
    Safe mode: not detected
    MySQL client: 5.5.60-MariaDB
    MySQL server: 5.6.42-log
    Free disk space: 204.16 GB
    Extensions: Core, date, ereg, libxml, openssl, pcre, sqlite3, zlib, bz2, calendar, ctype, curl, hash, fileinfo, filter, ftp, gettext, gmp, SPL, iconv, intl, pcntl, session, standard, posix, readline, Reflection, Phar, shmop, SimpleXML, sockets, mbstring, sysvmsg, sysvsem, sysvshm, tokenizer, wddx, xml, cgi-fcgi, bcmath, dba, dom, gd, imap, json, ldap, exif, mcrypt, mssql, mysql, mysqli, odbc, PDO, pdo_dblib, pdo_mysql, PDO_ODBC, pdo_pgsql, pdo_sqlite, pgsql, pspell, snmp, soap, tidy, xmlreader, xmlrpc, xmlwriter, xsl, zip, mhash, ionCube Loader, Zend OPcache
    GD: Yes
    ImageMagick: No
    PHP max upload size: 20M
    PHP max form post size: 20M
    PHP memory limit: 64M
    Total max uploadable file size: 20M
    Resource folder writeable: Yes
    Session timeout: 24 minutes
    Native JSON: Yes
    Filter functions: Yes
    Transliteration functions: Yes
    PATH: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin
    PWD: /var/www/fcgi
    PHP_FCGI_MAX_REQUESTS: 100
    ORIG_SCRIPT_NAME: /fcgi-bin/php56-cgi
    ORIG_PATH_TRANSLATED: /home/linweb23/a/arthur.web-design.wales/user/htdocs/admin/core/settings/diagnostics/index.php
    ORIG_PATH_INFO: /admin/core/settings/diagnostics/index.php
    ORIG_SCRIPT_FILENAME: /var/www/fcgi/php56-cgi
    SCRIPT_NAME: /admin/core/settings/diagnostics/index.php
    REQUEST_URI: /admin/core/settings/diagnostics/?extended
    QUERY_STRING: extended
    REQUEST_METHOD: GET
    SERVER_PROTOCOL: HTTP/1.0
    GATEWAY_INTERFACE: CGI/1.1
    REDIRECT_URL: /admin/core/settings/diagnostics/index.php
    REDIRECT_QUERY_STRING: extended
    REMOTE_PORT: 43962
    SCRIPT_FILENAME: /home/linweb23/a/arthur.web-design.wales/user/htdocs/admin/core/settings/diagnostics/index.php
    SERVER_ADMIN: support@fasthosts.com
    CONTEXT_DOCUMENT_ROOT: /var/www/fcgi/
    CONTEXT_PREFIX: /fcgi-bin/
    REQUEST_SCHEME: http
    DOCUMENT_ROOT: /home/linweb23/a/arthur.web-design.wales/user/htdocs
    REMOTE_ADDR: 91.103.188.194
    SERVER_PORT: 80
    SERVER_ADDR: 127.0.0.1
    SERVER_NAME: arthur.web-design.wales
    SERVER_SOFTWARE: Apache
    HTTP_UPGRADE_INSECURE_REQUESTS: 1
    HTTP_COOKIE: _ga=GA1.2.1589248101.1537449823; PHPSESSID=vq8p5qle5nejsmengd0cil74v1; cmsa=1
    HTTP_REFERER: https://arthur.web-design.wales/admin/core/settings/diagnostics/
    HTTP_ACCEPT_ENCODING: gzip, deflate
    HTTP_ACCEPT_LANGUAGE: en-GB,en;q=0.5
    HTTP_ACCEPT: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
    HTTP_USER_AGENT: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:63.0) Gecko/20100101 Firefox/63.0
    HTTP_CONNECTION: close
    HTTP_X_FORWARDED_FOR: 91.103.188.194
    HTTP_X_REAL_IP: 91.103.188.194
    HTTP_HOST: arthur.web-design.wales
    UNIQUE_ID: W@mg9SQ9Vf-6Ekn4surXxgAAAA0
    on: 127.0.0.1
    REDIRECT_STATUS: 200
    REDIRECT_HANDLER: application/x-httpd-php56
    REDIRECT_UNIQUE_ID: W@mg9SQ9Vf-6Ekn4surXxgAAAA0
    REDIRECT_on: 127.0.0.1
    FCGI_ROLE: RESPONDER
    PHP_SELF: /admin/core/settings/diagnostics/index.php
    REQUEST_TIME_FLOAT: 1542037749.194
    REQUEST_TIME: 1542037749

Here are the cart.html template:

<div class="wrapper cols2-nav-right">   
    <div class="primary-content">

<perch:if id="product_count" match="gt" value="0">
    <h1>Your cart (<perch:shop id="item_count" />)</h1>
    <perch:form id="cart" app="perch_shop">

        <perch:input type="submit" value="Update" hidden="true" aria-hidden="true" />

        <table class="cart">
            <tr>
                <th></th>
                <th>Code</th>
                <th>Item</th>
                <th>Quantity</th>
                <th>Price</th>
                <th>Total</th>
            </tr>
            <perch:cartitems>
                <tr>
                    <td><perch:cartitem id="image" type="image" width="80" height="80" density="1.6" crop="true" output="tag" /></td>
                    <td><perch:cartitem id="sku" /></td>
                    <td>
                        <b><perch:cartitem id="title" /></b>
                        <p><i><perch:cartitem id="variant_desc" /></i></p>
                        <div class="desc">
                            <perch:cartitem id="description" type="textarea" markdown="true" />
                        </div>
                        <button type="submit" class="remove_cart" name="del:<perch:cartitem id="identifier" />" value="1">
                            Remove from cart
                        </button>
                    </td>
                    <td><perch:input id="qty:<perch:cartitem id="identifier" />" value="<perch:cartitem id="quantity" />" type="number" min="0" /></td>
                    <td class="money"><perch:cartitem id="price_without_tax" /></td>
                    <td class="money"><perch:cartitem id="total_without_tax_formatted" /></td>
                </tr>
            </perch:cartitems>

            <perch:if id="total_discounts" match="gt" value="0.00">
                <tr class="total">
                    <th colspan="5">
                        Discount (<perch:shop id="discount_code" />)
                    </th>
                    <td class="money">
                        <perch:shop id="total_discounts_formatted" />
                    </td>
                </tr>
                <tr class="total">
                    <th colspan="5">
                        Total
                    </th>
                    <td class="money">
                        <perch:shop id="total_items_discounted_formatted" />
                    </td>
                </tr>
            <perch:else />
                <tr class="total">
                    <th colspan="5">
                        Total
                    </th>
                    <td class="money">
                        <perch:shop id="total_items_formatted" />
                    </td>
                </tr>
            </perch:if>
            <tr class="total">
                <th colspan="5">
                    Tax
                </th>
                <td class="money">
                    <perch:shop id="total_tax_formatted" />
                </td>
            </tr>
            <tr class="total">
                <th colspan="5">
                    Grand total
                </th>
                <td class="money">
                    <perch:shop id="grand_total_formatted" />
                </td>
            </tr>
        </table>

        <div class="discount">
            <perch:label for="discount">
                Discount code
                <perch:input type="text" id="discount_code" />
            </perch:label>
        </div>

        <perch:input type="submit" value="Update" />

    </perch:form>

    <p>
        <a href="checkout">Checkout now</a>
    </p>

<perch:else />
<h1>Your cart</h1>

<p>Your cart is empty.</p>
</perch:if>





</div>
</div>





<style>
.cart {
    width: 100%;
    border-collapse: collapse;
}

.cart th {
    font-weight: 600;
}

.cart td,
.cart th {
    border: 1px solid #efefef;
    vertical-align: top;
    padding: 3px;
}

.cart .total,
.cart .money {
    text-align: right;
}

.discount {
    max-width: 300px;
}

.desc {
    font-size: small;
}

b {
    font-weight: 600;
    color: rgba(0, 0, 0, 0.6);
}

i {
    font-style: italic;
    font-size: small;
    color: rgba(0, 0, 0, 0.6);
}

.remove_cart {
    background: none;
    border: 0;
    padding: 0;
    margin: 0;
    text-decoration: underline;
}

input[type=number] {
    width: 35px;
}
</style>

Here is the product.html template:

<perch:shop id="sku" type="text" label="SKU" required="true" order="1" />
<perch:shop id="title" type="text" label="Title" required="true" order="2" />
<perch:shop id="slug" type="slug" editable="true" indelible="true" label="Slug" for="title sku" order="10" divider-before="Meta data" />
<perch:shop id="description" type="textarea" label="Description" editor="markitup" order="3" markdown="true" size="s" />
<perch:shop id="image" type="image" label="Main product image" order="4" width="800" />
<perch:shop id="image" type="image" width="80" height="80" density="1.6" crop="true" />
<perch:shop id="status" type="shop_status" label="Status" />

<perch:shop id="brand" type="shop_brand" label="Brand" allowempty="true" />

<perch:categories id="category" set="products" label="Category">
    <perch:category id="catTitle" />
</perch:categories>

<perch:shop id="catalog_only" type="shop_catalog_only" label="Catalog only" />
<perch:shop id="price" type="shop_currency_value" label="Price" divider-before="Pricing" size="s" min="0" step="any" />
<perch:shop id="sale_price" type="shop_currency_value" label="Sale price" size="s" min="0" step="any" />
<perch:shop id="trade_price" type="shop_currency_value" label="Trade price" size="s" min="0" step="any" runway="true" />
<perch:shop id="on_sale" type="checkbox" value="1" label="Use sale price" />
<perch:shop id="tax_group" type="shop_tax_group" label="Tax group" required="true" />


<perch:shop id="stock_status" type="shop_stock_status" label="Stock status" divider-before="Stock" required="true" />
<perch:shop id="stock_level" type="number" label="Stock level" size="s" />
<perch:shop id="stock_location" type="shop_stock_location" label="Count stock" />
<perch:shop id="max_in_cart" type="number" label="Max quantity in cart" size="s" />

<perch:shop id="requires_shipping" type="shop_requires_shipping" label="Requires shipping" divider-before="Shipping" />
<perch:shop id="weight" type="number" label="Shipping weight" size="s" />
<perch:shop id="width" type="number" label="Width" size="s" />
<perch:shop id="height" type="number" label="Height" size="s" />
<perch:shop id="depth" type="number" label="Depth" size="s" />

<perch:form id="add_to_cart" app="perch_shop" action="/cart.php">
    <perch:input id="product" type="hidden" env-autofill="false" value="<perch:shop id="productID" type="hidden" env-autofill="false" />" />
    <perch:input type="submit" value="Add to cart" />
</perch:form>