How to fix this HoltWinters Prediction code?

Question

Hi I get this error message when I run this code

model <- forecast:::forecast.HoltWinters(mod, h=(length(data.ts)-length(dataTrain)))

Error in copy_msts(object$x, fitted) : x and y should have the same number of observations In addition: There were 50 or more warnings (use warnings() to see the first 50)

And another code

model <- hw(dataTrain, initial = "optimal", h=(length(data.ts)-length(dataTrain)))

Error in hw(dataTrain, initial = "optimal", h = (length(data.ts) - length(dataTrain))) : I need at least 15 observations to estimate seasonality.

This is the code I used to predict the organic traffic

#Training and Test Split

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