After 3 intents my code passed but I 've had fails with logs like this:

Expected: undefined, instead got: '        A    \n        W    \n        W    \nPBBPTQOICUDRZ\n        N    \n        P    \n        U    \n        O    \n        Z    \n        C    \n        L    \n        U    \n        L    \n        M    \n        C    \n        N    \n        T    \n        X    \n        M    \n        T    \n        R    \n'

It seems random tests generate invalid strings.