Reported by @kallewoof here: https://github.com/bitcoin/bitcoin/pull/13917#issuecomment-412459298

```
$ ./bitcoin-cli createpsbt "[]" "[{\"$(./bitcoin-cli getnewaddress)\":0.01}]"
cHNidP8BACoCAAAAAAFAQg8AAAAAABepFG6Rty1Vk+fUOR4v9E6R6YXDFkHwhwAAAAAAAA==
$ ./bitcoin-cli decodepsbt cHNidP8BACoCAAAAAAFAQg8AAAAAABepFG6Rty1Vk+fUOR4v9E6R6YXDFkHwhwAAAAAAAA==
error code: -22
error message:
TX decode failed CDataStream::read(): end of data: unspecified iostream_category error
```

{
        return !(a == b);
    }
    template <typename Stream>
    inline void Serialize(Stream& s) const {
        
        s << PSBT_MAGIC_BYTES;
        
        SerializeToVector(s, PSBT_GLOBAL_UNSIGNED_TX);
        
        OverrideStream<Stream> os(&s, s.GetType(), s.GetVersion() | SERIALIZE_TRANSACTION_NO_WITNESS);
        SerializeToVector(os, *tx);
        
        for (auto& entry : unknown) {
            s << entry.first;
            s << entry.second;
        }
        
        s << PSBT_SEPARATOR;
        
        for (const PSBTInput& input : inputs) {
            s << input;
        }
        
        for (const PSBTOutput& output : outputs) {
            s << output;
        }
    }
    template <typename Stream>
    inline void Unserialize(Stream& s) {