incorrect initialise params in FastDense after update to Flux v0.12.5

[KirillZubov]

Flux v0.12.5 has some changed so FastDense intilize params with nothing in the end now.

julia> FastChain(FastDense(1,12,Flux.σ),FastDense(12,1))
┌ Warning: Flux.zeros(size...) is deprecated, please use Flux.zeros32(size...) or Base.zeros(Float32, size...)
│   caller = ip:0x0
└ @ Core :-1
WARNING: both Flux and Iterators export "flatten"; uses of it in module DiffEqFlux must be qualified
WARNING: both Flux and Distributions export "params"; uses of it in module DiffEqFlux must be qualified
(::FastChain{Tuple{FastDense{typeof(σ), DiffEqFlux.var"#initial_params#89"{Vector{Union{Nothing, Float32}}}}, FastDense{typeof(identity), DiffEqFlux.var"#initial_params#89"{Vector{Union{Nothing, Float32}}}}}}) (generic function with 1 method)

julia> DiffEqFlux.initial_params(FastDense(1,3,Flux.σ))
4-element Vector{Union{Nothing, Float32}}:
 -0.8795005f0
 -0.021471778f0
 -1.0741668f0
   nothing

[DhairyaLGandhi]

Fixed by FluxML/Flux.jl#1670

[ChrisRackauckas]

Thanks!