Error when key doesn't evaluate to a boolean

[timholy]

Every example I've seen uses isodd; I don't know if that's a coincidence or whether it's deliberate, but I expected

count.(grouped(first, ["apple", "pear", "artichoke"]))

to yield something like Dict('a' => 2, 'p' => 1). Instead I get

julia> count.(grouped(first, ["apple", "pear", "artichoke"]))
ERROR: TypeError: non-boolean (String) used in boolean context
Stacktrace:
  [1] AsBool
    @ ~/.julia/packages/LazyGroupBy/h6njR/src/LazyGroupBy.jl:160 [inlined]
  [2] next
    @ ~/.julia/packages/Transducers/AgX5g/src/library.jl:53 [inlined]
  [3] (::Transducers.var"#69#71"{Char, Transducers.Reduction{Transducers.GroupBy{typeof(first), Transducers.Reduction{Transducers.Map{typeof(last)}, Transducers.Reduction{Transducers.Map{LazyGroupBy.AsBool{typeof(identity)}}, Transducers.BottomRF{typeof(+)}}}, Int64}, Transducers.BottomRF{Transducers.Completing{typeof(Transducers.right)}}}, String})(value::Nothing)
    @ Transducers ~/.julia/packages/Transducers/AgX5g/src/groupby.jl:162
  [4] generic_modify!!(f::Transducers.var"#69#71"{Char, Transducers.Reduction{Transducers.GroupBy{typeof(first), Transducers.Reduction{Transducers.Map{typeof(last)}, Transducers.Reduction{Transducers.Map{LazyGroupBy.AsBool{typeof(identity)}}, Transducers.BottomRF{typeof(+)}}}, Int64}, Transducers.BottomRF{Transducers.Completing{typeof(Transducers.right)}}}, String}, dict::Dict{Union{}, Union{}}, key::Char)
    @ BangBang.Extras ~/.julia/packages/BangBang/d7e1M/src/extras.jl:86
  [5] modify!!(f::Transducers.var"#69#71"{Char, Transducers.Reduction{Transducers.GroupBy{typeof(first), Transducers.Reduction{Transducers.Map{typeof(last)}, Transducers.Reduction{Transducers.Map{LazyGroupBy.AsBool{typeof(identity)}}, Transducers.BottomRF{typeof(+)}}}, Int64}, Transducers.BottomRF{Transducers.Completing{typeof(Transducers.right)}}}, String}, h::Dict{Union{}, Union{}}, key0::Char)
    @ BangBang.Extras ~/.julia/packages/BangBang/d7e1M/src/extras.jl:97
  [6] (::Transducers.var"#68#70"{Transducers.Reduction{Transducers.GroupBy{typeof(first), Transducers.Reduction{Transducers.Map{typeof(last)}, Transducers.Reduction{Transducers.Map{LazyGroupBy.AsBool{typeof(identity)}}, Transducers.BottomRF{typeof(+)}}}, Int64}, Transducers.BottomRF{Transducers.Completing{typeof(Transducers.right)}}}, String})(gstate::Dict{Union{}, Union{}}, iresult::Nothing)
    @ Transducers ~/.julia/packages/Transducers/AgX5g/src/groupby.jl:156
  [7] wrapping
    @ ~/.julia/packages/Transducers/AgX5g/src/core.jl:707 [inlined]
  [8] next
    @ ~/.julia/packages/Transducers/AgX5g/src/groupby.jl:154 [inlined]
  [9] macro expansion
    @ ~/.julia/packages/Transducers/AgX5g/src/core.jl:181 [inlined]
 [10] _foldl_array
    @ ~/.julia/packages/Transducers/AgX5g/src/processes.jl:187 [inlined]
 [11] __foldl__
    @ ~/.julia/packages/Transducers/AgX5g/src/processes.jl:182 [inlined]
 [12] #transduce#110
    @ ~/.julia/packages/Transducers/AgX5g/src/processes.jl:518 [inlined]
 [13] transduce
    @ ~/.julia/packages/Transducers/AgX5g/src/processes.jl:515 [inlined]
 [14] #transduce#109
    @ ~/.julia/packages/Transducers/AgX5g/src/processes.jl:501 [inlined]
 [15] transduce
    @ ~/.julia/packages/Transducers/AgX5g/src/processes.jl:500 [inlined]
 [16] #foldxl#115
    @ ~/.julia/packages/Transducers/AgX5g/src/processes.jl:956 [inlined]
 [17] #foldl#116
    @ ~/.julia/packages/Transducers/AgX5g/src/processes.jl:959 [inlined]
 [18] _impl_fold(fold::Function, kwargs::NamedTuple{(:init,), Tuple{Int64}}, rf::Function, xf::Transducers.Map{LazyGroupBy.AsBool{typeof(identity)}}, group::LazyGroupBy.GroupedBy{typeof(first), Vector{String}})
    @ LazyGroupBy ~/.julia/packages/LazyGroupBy/h6njR/src/LazyGroupBy.jl:105
 [19] impl(fold::typeof(foldl), kwargs::NamedTuple{(:init,), Tuple{Int64}}, rf::Function, xf::Transducers.Map{LazyGroupBy.AsBool{typeof(identity)}}, group::LazyGroupBy.GroupedBy{typeof(first), Vector{String}})
    @ LazyGroupBy ~/.julia/packages/LazyGroupBy/h6njR/src/LazyGroupBy.jl:112
 [20] impl(#unused#::typeof(count), #unused#::NamedTuple{(), Tuple{}}, group::LazyGroupBy.GroupedBy{typeof(first), Vector{String}})
    @ LazyGroupBy ~/.julia/packages/LazyGroupBy/h6njR/src/LazyGroupBy.jl:162
 [21] copy(bc::Base.Broadcast.Broadcasted{LazyGroupBy.GroupedByStyle, Nothing, typeof(count), Tuple{LazyGroupBy.GroupedBy{typeof(first), Vector{String}}}})
    @ LazyGroupBy ~/.julia/packages/LazyGroupBy/h6njR/src/LazyGroupBy.jl:91
 [22] materialize(bc::Base.Broadcast.Broadcasted{LazyGroupBy.GroupedByStyle, Nothing, typeof(count), Tuple{LazyGroupBy.GroupedBy{typeof(first), Vector{String}}}})
    @ Base.Broadcast ./broadcast.jl:883
 [23] top-level scope
    @ REPL[16]:1