FeatureVector out of range in function getMatches_neighratio(), how to fix it?

[llcc343]

Hi,
I want to use the function getMatches_neighratio(const vectorcv::Mat& A, const vector& i_A,
const vectorcv::Mat& B, const vector& i_B,
vector &i_match_A, vector &i_match_B), in my loop detection application which use ORB descriptor,but I found sometimes values in i_A would exceed the A's size ,how to fix it?