Cant resolve the syntax error in ruby language

I have this shopify snippet which displays the related products on product details page as well as on cart page
`{% for item in cart.items %}

{{ item.product.title }}

{% assign existed_handle = item.product.handle %} {% assign related_product_handles = '' %}

  {% for collection in item.product.collections %}
    {% if collection.title != 'Home page'%}
      {% assign current_collection = collections[collection.handle] %}
      {% for productItem in current_collection.products %}
        {% assign not_existed = true %}
        {% if existed_handle == productItem.handle %}
          {% assign not_existed = false %}
        {% endif %}

        {% if not_existed %}
          {% assign relatedHandleArr = related_product_handles | split: ',' %}
          {% unless relatedHandleArr contains productItem.handle %}
            {% if related_product_handles != '' %}
              {% assign related_product_handles = related_product_handles | append: ',' %}
            {% endif %}

            {% assign related_product_handles = related_product_handles | append: productItem.handle %}
          {% endunless %}
        {% endif %}
      {% endfor %}
    {% endif %}
  {% endfor %}

  {% if related_product_handles != '' %}
    <div class="gp-related-products" id="gp-related-products">
      <div class="related-title">
        <h2>{{ 'products.product.related_products' | t }}</h2>
      </div>
      <div class="related-items">
        {% assign count_product_main = 1 %}
        {% assign related_product_handle_items = related_product_handles | split: ',' %}
        {% assign related_product_handle_size = related_product_handle_items.size %}
        {% assign product_per_row = 5 %}
        {% assign total_rows = related_product_handle_size | divided_by: product_per_row | ceil %}
        {% assign limit = product_per_row | times: 2 %}
        {% assign row_count = 1 %}
        <div class="product_items slick-related">
          {% for related_product_handle in related_product_handle_items %}
            {% if count_product_main <= limit %}
              {% if count_product_main == 1 %}
                <div class="related-product-row">
              {% endif %}
                <div class="product-item">
                  {% assign productItem = all_products[related_product_handle] %}
                  {% include 'gp-product-grid' with product: productItem %}
                </div>
              {% if count_product_main == limit or count_product_main == related_product_handle_size %}
                </div>
                {% assign remaining_items = total_rows | minus: row_count | times: product_per_row %}
                {% if remaining_items > 0 %}
                  {% for i in (1..remaining_items) %}
                    <div class="product-item empty"></div>
                  {% endfor %}
                {% endif %}
                {% assign row_count = row_count | plus: 1 %}
                {% if row_count <= total_rows %}
                  <div class="related-product-row">
                {% endif %}
              {% elsif count_product_main | modulo: product_per_row == 0 %}



                </div>
                {% assign row_count = row_count | plus: 1 %}
                {% if row_count <= total_rows %}
                  <div class="related-product-row">
                {% endif %}
              {% endif %}
              {% assign count_product_main = count_product_main | plus: 1 %}
            {% endif %}
          {% endfor %}
        </div>
      </div>
    </div>
  {% endif %}
</div>

{% endfor %} ` I cant understand and resolve this error in this code `Liquid syntax error (snippets/gp-product-related line 57): Expected end_of_string but found pipe in "count_product_main | modulo: product_per_row == 0" Any kind of help will be very thankful. `

The report points to snippets/gp-product-related at line 57 and includes the failing Liquid expression. Read that expression and the surrounding conditional syntax; done would require a confirmed explanation or correction, but no repository change or test is specified.