Checking Problem with serialization

I ran into a problem when checking this task.

The dummy code seems to work fine; however, I experience strange behaviour when running checks on my code.

When I press Run & Check with the assertions uncommented:

if __name__ == '__main__':
    print(checkio([]))
    print(checkio([[5, 3, 4]]))
    print(checkio([[5, 3, 4], [2, 9, 3]]))

This data gets fed into the program instead of checking data, i.e. when checking input is [[0,0,1]], the program reads [[5, 3, 4]] instead.

I also received an error like in the attached picture (I don't get how is [1,0] is not a list of two integers).

I also get a 'ErrorUserRunSeondProcess' in the console.

When I comment-out the assertions, however, the checking doesn't occur at all. I see that the button-bar has the "Stop" button, however, there is no indication that the system is checking anything.

Perhaps, I re-ran the check too often and it caused some sort of system malfunction?

Please, aid me on this matter, as I think I got a working solution!