Transposing nx0 or 0xn SMartix yields empty Union as element type

I am having issues when transposing an SMatrix with a zero dimension. When transposing this matrix, the element type changes to Union{}. This happens with either one of the 2 dimension being zero, and also with other types (e.g. Int64).

This issue came up using v0.12.3 and v0.12.2. In v0.12.1 the element type stays the same, which I think is the expected and desired behavior.

Minimum (not) working example using v0.12.3 (and v0.12.2):

julia> using StaticArrays

julia> a = SMatrix{3,0,Float64,0}()
3×0 SArray{Tuple{3,0},Float64,2,0} with indices SOneTo(3)×SOneTo(0)

julia> a'
0×3 SArray{Tuple{0,3},Union{},2,0} with indices SOneTo(0)×SOneTo(3)

Working example using v0.12.1:

julia> using StaticArrays

julia> a = SMatrix{3,0,Float64,0}()
3×0 SArray{Tuple{3,0},Float64,2,0} with indices SOneTo(3)×SOneTo(0)

julia> a'
0×3 SArray{Tuple{0,3},Float64,2,0} with indices SOneTo(0)×SOneTo(3)

Reproduce the issue with the Julia examples for SMatrix{3,0,Float64,0} and its transpose, comparing StaticArrays v0.12.3 with v0.12.1. Trace the transpose operation and verify that zero-dimension matrices preserve their original element type, including the Int64 case described; done means the result no longer has element type Union{}.