Auto differentiation failure for aba()

[FenglongSong]

Hi,

I'm using aba() to calculate forward dynamics and I'm trying to get the derivatives using CppAd. I got the following error:
GreaterThanZero cannot be called for non-parameters, Aborted (core dumped)

When I attempted to replace return aba(mode, data, q, v, tau, fext) by simply returning a zero vector, it will work. Therefore, I think the error is caused by an if/else branch in the implementation of aba:

// https://github.com/stack-of-tasks/pinocchio/blob/master/src/algorithm/aba.hxx#L46
if (parent>0)
        data.v[i] += data.liMi[i].actInv(data.v[parent]);

Would there be any easy fix for that?

Of course if I just want to get derivatives w.r.t some terms like q, v, tau, I can just use functions in aba-derivatives.hpp. But in my case, there're other things relying on CppAd so I'm seeking a solution for the auto diff method. Suggestions will be much appreciated!