NUM_BANK returning -1 instead of three

[I98]

I have a es6 npm module that i use with js2py. It seems to work normally at the beginning, but after using a certain function for the about 10th time, it gets stuck in a long loop. After some debugging I found out what is causing the problem: The Js(len(args)) call in PyJsArgument init method returns -1 and somehow this comes out of NUM_BANK. If I comment out the NUM_BANK acceleration in the Js(val, Clamped=False): function the code works normally.

Any idea how this could be happening and why only after so many function calls?

[PiotrDabkowski]

The numbers should be immutable, can you include the code so that I can reproduce and debug?