Error with constructor after Tables 1.8

[JackDunnNZ]

Not sure this is the right place to file this, but after Tables 1.8 (in particular JuliaData/Tables.jl#288) the following code gives an error:

julia> using DataFrames, CategoricalArrays

julia> d = DataFrame(x=allowmissing(categorical(["a"])))

julia> vcat(d, d)
ERROR: MethodError: no method matching (CategoricalVector{Union{Missing, String}, UInt32})(::Missing, ::Int64)
Closest candidates are:
  (CategoricalArray{T, 1, R})(::UndefInitializer, ::Int64; levels, ordered) where {T, R} at ~/.julia/packages/CategoricalArrays/zg8z5/src/array.jl:191
Stacktrace:
 [1] allocatecolumn(T::Type, len::Int64)
   @ Tables ~/.julia/packages/Tables/Rophz/src/fallbacks.jl:107
 [2] _vcat(dfs::Vector{AbstractDataFrame}; cols::Symbol)
   @ DataFrames ~/.julia/packages/DataFrames/a6np0/src/abstractdataframe/abstractdataframe.jl:1871
 [3] #reduce#130
   @ ~/.julia/packages/DataFrames/a6np0/src/abstractdataframe/abstractdataframe.jl:1761 [inlined]
 [4] #vcat#129
   @ ~/.julia/packages/DataFrames/a6np0/src/abstractdataframe/abstractdataframe.jl:1679 [inlined]
 [5] vcat(::DataFrame, ::DataFrame)
   @ DataFrames ~/.julia/packages/DataFrames/a6np0/src/abstractdataframe/abstractdataframe.jl:1679
 [6] top-level scope
   @ REPL[4]:1

(docs) pkg> st -m DataFrames CategoricalArrays Tables
  [324d7699] CategoricalArrays v0.10.6
  [a93c6f00] DataFrames v1.3.5
  [bd369af6] Tables v1.8.0

It looks like a new constructor taking missing as the first arg might be needed?

[bkamins]

see JuliaData/Tables.jl#298 (for the time being, before the issue is resolved, I recommend you implement this patch to make things work)

[bkamins]

The constructor you mention still might be added. Let us see what @nalimilan decides.

[nalimilan]

Yes we could implement that constructor (though in practice it would be completely identical to the undef one). But please file a separate issue if you're interested in it, as this one mentions an error with Tables.jl which is now fixed there.