Error "type Dict has no field"

[jariji]

julia> DataFrame([Dict("a" => 1), Dict()])
ERROR: type Dict has no field a
Stacktrace:
  [1-10] ⋮ internal
       @ Base, Tables, DataFrames, Unknown
    [11] DataFrame(x::Vector{Dict})
       @ DataFrames ~/.julia/packages/DataFrames/58MUJ/src/other/tables.jl:48
Use `err` to retrieve the full stack trace.

julia> DataFrame([Dict("a" => 1), Dict("a" => 2)])
2×1 DataFrame
 Row │ a     
     │ Int64 
─────┼───────
   1 │     1
   2 │     2

I think this error message isn't that clear. Perhaps better:

Dict at index 2 has no key "a".

[bkamins]

I am transferring it to Tables.jl as the issue is with column building mechanism that is implemented there:

julia> DataFrame([Dict("a" => 1), Dict()])
ERROR: type Dict has no field a
Stacktrace:
  [1] getproperty
    @ Base .\Base.jl:37 [inlined]
  [2] getcolumn(x::Dict{Any, Any}, nm::Symbol)
    @ Tables ~\.julia\packages\Tables\NSGZI\src\Tables.jl:102
  [3] getcolumn
    @ Tables ~\.julia\packages\Tables\NSGZI\src\tofromdatavalues.jl:73 [inlined]
  [4] eachcolumns(::typeof(Tables.add_or_widen!), ::Tables.Schema{(:a,), nothing}, ::Tables.IteratorRow{Dict{Any, Any}}, ::Tuple{Vector{Int64}}, ::Int64, ::Vararg{Any})
    @ Tables ~\.julia\packages\Tables\NSGZI\src\utils.jl:127
  [5] __buildcolumns(rowitr::Tables.IteratorWrapper{Vector{Dict}}, st::Int64, sch::Tables.Schema{(:a,), nothing}, columns::Tuple{Vector{Int64}}, rownbr::Int64, updated::Base.RefValue{Any})
    @ Tables ~\.julia\packages\Tables\NSGZI\src\fallbacks.jl:174
  [6] _buildcolumns(rowitr::Tables.IteratorWrapper{Vector{…}}, row::Tables.IteratorRow{Dict{…}}, st::Int64, sch::Tables.Schema{(:a,), nothing}, columns::Tuple{Tables.EmptyVector}, updated::Base.RefValue{Any})
    @ Tables ~\.julia\packages\Tables\NSGZI\src\fallbacks.jl:198
  [7] buildcolumns
    @ ~\.julia\packages\Tables\NSGZI\src\fallbacks.jl:227 [inlined]
  [8] _columns
    @ ~\.julia\packages\Tables\NSGZI\src\fallbacks.jl:274 [inlined]
  [9] columns
    @ ~\.julia\packages\Tables\NSGZI\src\fallbacks.jl:258 [inlined]
 [10] DataFrame(x::Vector{Dict}; copycols::Nothing)
    @ DataFrames ~\.julia\packages\DataFrames\58MUJ\src\other\tables.jl:57
 [11] DataFrame(x::Vector{Dict})
    @ DataFrames ~\.julia\packages\DataFrames\58MUJ\src\other\tables.jl:48