rm use of Nothing as fill, we want to use Missing

Author: rayegun

src/operations/operationutils.jl

@@ -110,16 +110,9 @@ Determine type of the output of a typed operator.
 """
 function ztype end
 
-_promotefill(::AbstractGBArray{<:Any, Nothing}, ::AbstractGBArray{<:Any, Nothing}, op) = nothing
-_promotefill(::AbstractGBArray{<:Any, Nothing}, y, op) = nothing
-_promotefill(x, ::AbstractGBArray{<:Any, Nothing}, op) = nothing
 _promotefill(::AbstractGBArray{<:Any, Missing}, ::AbstractGBArray{<:Any, Missing}, op) = missing
-_promotefill(::AbstractGBArray{<:Any, Missing}, y, op) = nothing
-_promotefill(x, ::AbstractGBArray{<:Any, Missing}, op) = nothing
-_promotefill(::AbstractGBArray{<:Any, Nothing}, ::AbstractGBArray{<:Any, Missing}, op) = nothing
-_promotefill(::AbstractGBArray{<:Any, Missing}, ::AbstractGBArray{<:Any, Nothing}, op) = nothing
-_promotefill(::AbstractGBArray{<:Any, Nothing}, ::AbstractGBArray{<:Any, <:Any}, op) = nothing
-_promotefill(::AbstractGBArray{<:Any, <:Any}, ::AbstractGBArray{<:Any, Nothing}, op) = nothing
+_promotefill(::AbstractGBArray{<:Any, Missing}, y, op) = missing
+_promotefill(x, ::AbstractGBArray{<:Any, Missing}, op) = missing
 _promotefill(::AbstractGBArray{<:Any, Missing}, ::AbstractGBArray{<:Any, <:Any}, op) = missing
 _promotefill(::AbstractGBArray{<:Any, <:Any}, ::AbstractGBArray{<:Any, Missing}, op) = missing
 

src/operations/transpose.jl

@@ -67,10 +67,6 @@ end
 #This is ok per the GraphBLAS Slack channel. Should change its effect on Complex input.
 LinearAlgebra.adjoint(A::GBVecOrMat) = transpose(A)
 
-#arrrrgh, type piracy.
-# TODO: avoid this if possible
-LinearAlgebra.transpose(::Nothing) = nothing
-
 Base.unsafe_convert(::Type{Ptr{T}}, A::LinearAlgebra.AdjOrTrans{<:Any, <:AbstractGBArray}) where {T} = 
 throw(ArgumentError("Cannot convert $(typeof(A)) directly to a pointer. Please use copy."))