Sanitize URL before parsing (#17559)

URL strings that have leading or trailing spaces raise exceptions when
parsing.

app/helpers/articles_helper.rb

@@ -52,6 +52,7 @@ module ArticlesHelper
   end
 
   def get_host_without_www(url)
+    url = url.strip
     url = "http://#{url}" if Addressable::URI.parse(url).scheme.nil?
     host = Addressable::URI.parse(url).host.downcase
     host.gsub!("medium.com", "Medium")

spec/helpers/articles_helper_spec.rb

@@ -21,6 +21,11 @@ describe ArticlesHelper do
       host = helper.get_host_without_www("www.example.com")
       expect(host).to eq "example.com"
     end
+
+    it "can handle URLs with leading and trailing whitespace" do
+      host = helper.get_host_without_www(" www.example.com ")
+      expect(host).to eq "example.com"
+    end
   end
 
   describe "#image_tag_or_inline_svg_tag" do