ERROR: MethodError: Cannot `convert` an object of type Nothing to an object of type Int64

[mthelm85]

I'm reading in a .csv file with DelimitedFiles like this:

data = readdlm("clean_data.csv", ',', Int, header=true)

data[1] is a 230×19 Array{Int64,2} and data[2] is a 1×19 Array{AbstractString,2}. However, when I run

gsreg("y *", data)

I get the following error (even though my data doesn't have any Nothing types in it):

ERROR: MethodError: Cannot `convert` an object of type Nothing to an object of type Int64
Closest candidates are:
  convert(::Type{T}, ::T) where T<:Number at number.jl:6
  convert(::Type{T}, ::Number) where T<:Number at number.jl:7
  convert(::Type{T}, ::Ptr) where T<:Integer at pointer.jl:23
  ...
Stacktrace:
 [1] setindex!(::Dict{Symbol,Int64}, ::Nothing, ::Symbol) at .\dict.jl:380
 [2] get_result_header(::Array{Symbol,1}, ::Bool, ::Bool, ::Nothing, ::Nothing, ::Array{Any,1}, ::Bool) at C:\Users\mthel\.julia\packages\GlobalSearchRegression\afyOH\src\utils.jl:90
 [3] GlobalSearchRegression.GSRegResult(::Symbol, ::Array{Symbol,1}, ::Array{Float32,2}, ::Bool, ::Int64, ::Array{Any,1}, ::Bool, ::Bool, ::Bool, ::Nothing, ::Nothing, ::Array{Any,1}, ::Type, ::Bool, ::GlobalSearchRegression.var"#1#2", ::Nothing) at C:\Users\mthel\.julia\packages\GlobalSearchRegression\afyOH\src\gsreg_result.jl:58
 [4] #gsreg#23 at C:\Users\mthel\.julia\packages\GlobalSearchRegression\afyOH\src\core.jl:50 [inlined]
 [5] (::GlobalSearchRegression.var"#kw##gsreg")(::NamedTuple{(:datanames, :intercept, :outsample, :criteria, :ttest, :vectoroperation, :modelavg, :residualtest, :time, :summary, :datatype, :orderresults, :onmessage, :parallel),Tuple{Array{Any,1},Bool,Int64,Array{Any,1},Bool,Bool,Bool,Nothing,Nothing,Nothing,DataType,Bool,GlobalSearchRegression.var"#1#2",Nothing}}, ::typeof(gsreg), ::Symbol, ::Array{Symbol,1}, ::Array{Float32,2}) at .\none:0      
 [6] #gsreg#22(::Bool, ::Int64, ::Array{Any,1}, ::Bool, ::String, ::Bool, ::Bool, ::Nothing, ::Nothing, ::Nothing, ::Nothing, ::Nothing, ::Bool, ::GlobalSearchRegression.var"#1#2", ::Nothing, ::typeof(gsreg), ::Array{Symbol,1}, ::Array{Int64,2}, ::Array{Any,1}) at C:\Users\mthel\.julia\packages\GlobalSearchRegression\afyOH\src\interface.jl:292
 [7] #gsreg at .\none:0 [inlined]
 [8] #gsreg#21(::Array{AbstractString,2}, ::Bool, ::Int64, ::Array{Any,1}, ::Bool, ::String, ::Bool, ::Bool, ::Nothing, ::Nothing, ::Nothing, ::Nothing, ::Nothing, ::Bool, ::GlobalSearchRegression.var"#1#2", ::Nothing, ::typeof(gsreg), ::Array{Symbol,1}, ::Tuple{Array{Int64,2},Array{AbstractString,2}}) at C:\Users\mthel\.julia\packages\GlobalSearchRegression\afyOH\src\interface.jl:173
 [9] (::GlobalSearchRegression.var"#kw##gsreg")(::NamedTuple{(:datanames, :intercept, :outsample, :criteria, :ttest, :method, :vectoroperation, :modelavg, :residualtest, :time, :summary, :resultscsv, :csv, :orderresults, :onmessage, :parallel),Tuple{Array{AbstractString,2},Bool,Int64,Array{Any,1},Bool,String,Bool,Bool,Nothing,Nothing,Nothing,Nothing,Nothing,Bool,GlobalSearchRegression.var"#1#2",Nothing}}, ::typeof(gsreg), ::Array{Symbol,1}, ::Tuple{Array{Int64,2},Array{AbstractString,2}}) at .\none:0
 [10] #gsreg#20(::Nothing, ::Bool, ::Int64, ::Array{Any,1}, ::Bool, ::String, ::Bool, ::Bool, ::Nothing, ::Nothing, ::Nothing, ::Nothing, ::Nothing, ::Bool, ::GlobalSearchRegression.var"#1#2", ::Nothing, ::typeof(gsreg), ::Array{String,1}, ::Tuple{Array{Int64,2},Array{AbstractString,2}}) at C:\Users\mthel\.julia\packages\GlobalSearchRegression\afyOH\src\interface.jl:117
 [11] (::GlobalSearchRegression.var"#kw##gsreg")(::NamedTuple{(:datanames, :intercept, :outsample, :criteria, :ttest, :method, :vectoroperation, :modelavg, :residualtest, :time, :summary, :resultscsv, :csv, :orderresults, :onmessage, :parallel),Tuple{Nothing,Bool,Int64,Array{Any,1},Bool,String,Bool,Bool,Nothing,Nothing,Nothing,Nothing,Nothing,Bool,GlobalSearchRegression.var"#1#2",Nothing}}, ::typeof(gsreg), ::Array{String,1}, ::Tuple{Array{Int64,2},Array{AbstractString,2}}) at .\none:0
 [12] gsreg(::String, ::Tuple{Array{Int64,2},Array{AbstractString,2}}) at C:\Users\mthel\.julia\packages\GlobalSearchRegression\afyOH\src\interface.jl:67
 [13] top-level scope at REPL[177]:1