Generate a products csv file to make it easier to migrate from Big Cartel to Shopify

bigcartel_to_shopify_csv.rb

#script created by Matt Anderson, http://tonkapark.com

require 'rubygems'
require 'bigcartel'
require 'csv'

# SET YOUR BIGCARTEL ID HERE
STORE = 'ugmonk'

# SET THE BEST NAME FOR ANY DROP DOWN OPTIONS
BC_OPTION_NAME = "Size"

class Shopify <  
  Struct.new(:handle, :title, :body,:vendor,:type,:tags,
  :opt1_name, :opt1_val,
  :opt2_name, :opt2_val,
  :opt3_name, :op3_val,
  :sku,:grams,:inventory_tracker,:qty, :inventory_policy, :fullfillment, 
  :price,:compare_at, :requires_shipping, :taxable, :image_src)
end

s = BigCartel.store(STORE)

rows = Array.new

  s.products.each do |p|
    row = Shopify.new
    row.handle = p.permalink
    row.title = p.name
    row.body = p.description
    row.vendor = s.name
    row.type = p.categories.first.name
    row.tags = p.categories.collect{|x| x.name}.join(', ')
    
    
    if p.has_default_option
      row.opt1_name = BC_OPTION_NAME
      row.opt1_val = p.option.name
      price = p.option.price
    else
      row.opt1_name = BC_OPTION_NAME
      row.opt1_val = p.options.first.name
      price = p.options.first.price     
    end
     
    row.price = price    
    row.image_src = p.image.url 
    
    #defaults to allow import to shopify    
    row.qty = 0
    row.inventory_policy = 'deny'    
    row.fullfillment = 'manual'
    row.sku = p.id  
    
    rows.push(row)
    
    #additional variants
    unless p.has_default_option    
      for i in 1..p.options.length-1 do
        opt_row = Shopify.new
        opt_row.handle = p.permalink
        opt_row.opt1_name = BC_OPTION_NAME
        opt_row.opt1_val = p.options[i].name
        opt_row.price = p.options[i].price
        
        #defaults to allow import to shopify    
        opt_row.qty = 0
        opt_row.inventory_policy = 'deny'    
        opt_row.fullfillment = 'manual'
        opt_row.sku = p.id
        
        rows.push(opt_row)
      end
    
    end
    
    #additional images
    for i in 1..p.images.length-1 do
       img_row = Shopify.new
       img_row.handle = p.permalink
       img_row.image_src = p.images[i].url
       rows.push(img_row)
    end
    
  end
    
file_name = "#{STORE}.csv"
CSV.open(file_name, 'w') do |csv|
  header_row = ["Handle", "Title", "Body (HTML)", "Vendor", "Type", "Tags", "Option1 Name", "Option1 Value", "Option2 Name", "Option2 Value", "Option3 Name", "Option3 Value", "Variant SKU", "Variant Grams", "Variant Inventory Tracker", "Variant Inventory Qty", "Variant Inventory Policy", "Variant Fulfillment Service", "Variant Price", "Variant Compare At Price", "Variant Requires Shipping", "Variant Taxable", "Image Src"]
  csv << header_row
  rows.each { |p|
    csv << p
  }
end

I tried running this but I get an error:
bigcartel_to_shopify_csv.rb:26:in <main>': undefined methodeach' for nil:NilClass (NoMethodError)

Looks like it's parsing the data though, just stopping before the csv file is created.

I get the following error:

Conn close
Traceback (most recent call last):
2: from ../1123342/bigcartel_to_shopify_csv.rb:26:in <main>' 1: from ../1123342/bigcartel_to_shopify_csv.rb:26:in each'
../1123342/bigcartel_to_shopify_csv.rb:47:in block in <main>': undefined method url' for nil:NilClass (NoMethodError)