Add exception for 423 API error code

Author: kirillplatonov

lib/shopify_graphql/client.rb

@@ -47,6 +47,8 @@ def handle_response(response)
         raise PreconditionFailed.new(parsed_body(response), code: response.code)
       when 422
         raise ResourceInvalid.new(parsed_body(response), code: response.code)
+      when 423
+        raise ShopLocked.new(parsed_body(response), code: response.code)
       when 429, 430
         raise TooManyRequests.new(parsed_body(response), code: response.code)
       when 401...500

lib/shopify_graphql/exceptions.rb

@@ -60,6 +60,10 @@ class ResourceGone < ClientError # :nodoc:
   class PreconditionFailed < ClientError # :nodoc:
   end
 
+  # 423 Locked
+  class ShopLocked < ClientError # :nodoc:
+  end
+
   # 429 Too Many Requests
   class TooManyRequests < ClientError # :nodoc:
   end