If a parser throwing an error due to duplicate fields causes a DoS, then the same is going to happen when it throws an error due to invalid encoding... So, I d

If a parser throwing an error due to duplicate fields causes a DoS, then the same is going to happen when it throws an error due to invalid encoding... So, I don't think that's a relevant critique. I think any ambiguous case in parsing untrusted user input should raise an error, and anyone working on code with untrusted data should be ready to handle errors