Package crashes on duplicated variables

[krystian8207]

See:

formula <- log(y) ~
    xs(x, method_opts = list(type = type)) * z + xf(t) + w ^ 2 + I(z ^ 2)
extract_formula_var_names(formula_4, data) # gives c("y", "x", "z", "t", "w")
get_formula_raw_components(formula_terms) # gives
    c("xs(x, method_opts = list(type = type))", "z", "xf(t)", "w", "I(z^2)")

Find out what logic should be here implemented do match z variable.