Polynominal regression optimisation - feature and degree

Hi, i am working on regression model and it is going fine. now i try to find the best set of features and best degree (parameter) for my predictor - i can do it seperately, but cannot in one (nested) loop - do you have any idea how to do it properly, so i can read the outcomes of feature x degree combinations?

i enclose two screenshots with working flows and one which is giving error message

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