furnibot.rb

require "mediawiki-butt"

butt = MediaWiki::Butt.new("http://habbo.gamepedia.com")
butt.login("ESAEBSAD", "-REDACTED-")

butt.get_category_members("Category:Has furni image", 5000).each do |page|
  page = page.tr(":", "")
  
  big_file = butt.get_text("File:#{page}.png")
  if big_file != nil && big_file != "{{Furniture Image}}"
      butt.edit("File:#{page}.png", "{{Furniture Image}}")
  end
  
  small_file = butt.get_text("File:#{page} small.png")
  if small_file != nil && small_file != "{{Furniture Image}}"
      butt.edit("File:#{page} small.png", "{{Furniture Image}}")
  end
end

Use dis code instead :)

require "mediawiki-butt"

butt = MediaWiki::Butt.new("http://habbo.gamepedia.com")
butt.login("ESAEBSAD", "-REDACTED-")

butt.get_category_members("Category:Furni", 5000).each do |page|
  page = page.tr(":", "")

  page_text = butt.get_categories_in_page(page)

  if !page_text.include? "Missing furni image"
    big_file = butt.get_text("File:#{page}.png")
    if big_file != nil && big_file != "{{Furniture Image}}"
      butt.edit("File:#{page}.png", "{{Furniture Image}}")
    end
  end

  if !page_text.include? "Missing small furni image"
    small_file = butt.get_text("File:#{page} small.png")
    if small_file != nil && small_file != "{{Furniture Image}}"
      butt.edit("File:#{page} small.png", "{{Furniture Image}}")
    end
  end
end