Thanks for helping to bring this issue to our attention. I reviewed the API errors you mentioned and was able to find that the one you received with respect to the collar occurred because due to an issue with the “Pet Supplies” template that occurred recently when some details associated with the template were updated.
If you open up the saved listing for this product, select the “Pet Supplies” template from the “Select Template” interface again, I believe that you will then be able to post the listing successfully be attempting to post or schedule it again.
I am unable to tell which template that the other listing had selected when the errors occurred, but I have a feeling that error was most likely a result of a similar problem. If you try using that template again in the future and you receive the same error, please let us know and we will look into it further.