julia> using RCall
julia> reval("library(tidyverse)")
julia> rcopy(reval("aes(x, y)"))
ERROR: LoadError: ArgumentError: malformed expression in formula ~x
Stacktrace:
  [1] var"@formula"(__source__::LineNumberNode, __module__::Module, ex::Any)
    @ StatsModels ~/.julia/packages/StatsModels/Wzvuu/src/formula.jl:62
  [2] eval
    @ ./boot.jl:370 [inlined]
  [3] rcopy(#unused#::Type{StatsModels.FormulaTerm}, l::Ptr{LangSxp})
    @ RCall ~/.julia/packages/RCall/gOwEW/src/convert/formula.jl:41
  [4] rcopy(s::Ptr{LangSxp}; kwargs::Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})
    @ RCall ~/.julia/packages/RCall/gOwEW/src/convert/default.jl:14
  [5] rcopy
    @ ~/.julia/packages/RCall/gOwEW/src/convert/default.jl:8 [inlined]
  [6] rcopy(#unused#::Type{Any}, s::Ptr{LangSxp})
    @ RCall ~/.julia/packages/RCall/gOwEW/src/convert/base.jl:21
  [7] rcopy(::Type{OrderedCollections.OrderedDict{Symbol, Any}}, s::Ptr{VecSxp}; normalizenames::Bool)
    @ RCall ~/.julia/packages/RCall/gOwEW/src/convert/base.jl:174
  [8] rcopy(::Type{OrderedCollections.OrderedDict{Symbol, Any}}, s::Ptr{VecSxp})
    @ RCall ~/.julia/packages/RCall/gOwEW/src/convert/base.jl:165
  [9] rcopy(s::Ptr{VecSxp}; kwargs::Base.Pairs{Symbol, Union{}, Tuple{}, NamedTuple{(), Tuple{}}})
    @ RCall ~/.julia/packages/RCall/gOwEW/src/convert/default.jl:18
 [10] rcopy
    @ ~/.julia/packages/RCall/gOwEW/src/convert/default.jl:8 [inlined]
 [11] #rcopy#16
    @ ~/.julia/packages/RCall/gOwEW/src/convert/default.jl:6 [inlined]
 [12] rcopy(r::RObject{VecSxp})
    @ RCall ~/.julia/packages/RCall/gOwEW/src/convert/default.jl:6
 [13] top-level scope
    @ REPL[50]:1
in expression starting at /home/ssahm/.julia/packages/RCall/gOwEW/src/convert/formula.jl:41