work around nothing passing to cfunction

Author: ChrisRackauckas

src/utils.jl

@@ -93,9 +93,9 @@ function vars!(vars, O)
 end
 
 @inline @generated function fast_invokelatest(f, ::Type{rt}, args...) where rt
-  tupargs = Expr(:tuple,args...)
+  tupargs = Expr(:tuple,(a==Nothing ? Int : a for a in args)...)
   quote
-    _f = $(Expr(:cfunction, Base.CFunction, :f, rt, :((Core.svec)($args...)), :(:ccall)))
-    return ccall(_f.ptr,rt,$tupargs,$((:(getindex(args,$i)) for i in 1:length(args))...))
+    _f = $(Expr(:cfunction, Base.CFunction, :f, rt, :((Core.svec)($((a==Nothing ? Int : a for a in args)...))), :(:ccall)))
+    return ccall(_f.ptr,rt,$tupargs,$((:(getindex(args,$i) === nothing ? 0 : getindex(args,$i)) for i in 1:length(args))...))
   end
 end