Use http scheme for url (#42)

* Use `http` scheme for url

* Fixup

* Fixup

src/exception_page.cr

@@ -26,6 +26,13 @@ abstract class ExceptionPage
         "all"
       end
     end
+
+    def host_from_context(context)
+      if host = context.request.headers["Host"]?
+        host = "http://#{host}"
+      end
+      host
+    end
   end
 
   include Helpers
@@ -67,7 +74,7 @@ abstract class ExceptionPage
     @headers = context.response.headers.to_h
     @method = context.request.method
     @path = context.request.path
-    @url = "#{context.request.headers["Host"]?}#{context.request.path}"
+    @url = "#{host_from_context(context)}#{context.request.path}"
     @query = context.request.query_params.to_s
     @session = context.response.cookies.to_h
   end