#453 fix typeo introduced in #389 (#454)

I introduced this bug in #389 - my apologies.  Fixes #453.

Author: baumgold

src/ArrowTypes/src/ArrowTypes.jl

@@ -119,8 +119,8 @@ This will then be available to access by overloading `ArrowTypes.JuliaType(::Val
 function arrowmetadata end
 const EMPTY_STRING = ""
 arrowmetadata(T) = EMPTY_STRING
-arrowmetadata(::Type{Union{T,Missing}}) where {T} = arrowmetadata{T}
-arrowmetadata(::Type{Union{T,Nothing}}) where {T} = arrowmetadata{T}
+arrowmetadata(::Type{Union{T,Missing}}) where {T} = arrowmetadata(T)
+arrowmetadata(::Type{Union{T,Nothing}}) where {T} = arrowmetadata(T)
 arrowmetadata(::Type{Nothing}) = EMPTY_STRING
 arrowmetadata(::Type{Missing}) = EMPTY_STRING
 arrowmetadata(::Type{Any}) = EMPTY_STRING

src/ArrowTypes/test/tests.jl

@@ -38,6 +38,8 @@ end
 @test !ArrowTypes.hasarrowname(Int)
 
 @test ArrowTypes.arrowmetadata(Int) == ""
+@test ArrowTypes.arrowmetadata(Union{Nothing,Int}) == ""
+@test ArrowTypes.arrowmetadata(Union{Missing,Int}) == ""
 
 @test ArrowTypes.JuliaType(1) === nothing
 @test ArrowTypes.JuliaType(1, Int) === nothing