lapply and ifelse condition with poly fit and scale in R

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I would like to calculate two function based on condition length. When lst argument is <=4 one function else second function, I tried with:

lapply(lst, function (x) ifelse((sapply(lst,length)<=4)==T,scale,
                                (fit <- lm(x ~ poly(seq(1:length(x)), 5, raw=TRUE)))
                                (d <- resid(fit)-mean(resid(fit)))/sd(resid(fit))))

but there is an error:

    Error in ifelse((sapply(lst, length) <= 4) == T, scale, (fit <- lm(x ~  : 
  unused argument (d <- resid(fit) - mean(resid(fit))/sd(resid(fit)))

How can I to calculate the fit and the z.score of the residuals in the same function when the length is more then 4?