jsval_to_ccarray bug when convert js array to c++

The following code works:

JS:
pi.Mime.test([
{
k1: {a:1, b:2, c:3},
k2: 123
}
]);

In C*+ it will use jsval_to_ccarray to convert the array to cocos2d::array.
Everything is fine now.

But when I change the JS code to:
pi.Mime.test;
Just reorder the two keys.
It will asset fail in js_manual_conversions.cpp’s line 1471.
The “k1” is convert normally, but the “k2” can’t convert to c*+ number, it’s js type is undefined.
I’m not sure if it’s spidermonkey’s bug.

My cocos2d-x version is 3.0 beta.
In 3.0 alpha0 no this bug, everything is fine.