SavingCallback broken?

[dkarrasch]

I took the example from the callback docs (slightly corrected for Julia 0.7+

using DiffEqCallbacks, OrdinaryDiffEq, LinearAlgebra
prob = ODEProblem((du, u, t) -> du .= u, rand(4,4), (0.0, 1.0))
saved_values = SavedValues(Float64, Tuple{Float64,Float64})
cb = SavingCallback((u, t, integrator) -> (tr(u), norm(u)), saved_values)
sol = solve(prob, Tsit5(), callback=cb)

and got

ERROR: MethodError: Cannot `convert` an object of type Nothing to an object of type Float64
Closest candidates are:
  convert(::Type{T<:Number}, ::T<:Number) where T<:Number at number.jl:6
  convert(::Type{T<:Number}, ::Number) where T<:Number at number.jl:7
  convert(::Type{T<:Number}, ::Base.TwicePrecision) where T<:Number at twiceprecision.jl:250
  ...
Stacktrace:
 [1] fill!(::Array{Float64,2}, ::Nothing) at ./array.jl:386
 [2] copyto! at ./broadcast.jl:808 [inlined]
 [3] materialize! at ./broadcast.jl:759 [inlined]
 [4] (::getfield(Main, Symbol("##9#10")))(::Array{Float64,2}, ::Nothing, ::Float64) at ./none:1
 [5] (::ODEFunction{false,getfield(Main, Symbol("##9#10")),UniformScaling{Bool},Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing})(::Array{Float64,2}, ::Nothing, ::Vararg{Any,N} where N) at /Users/karrasch/.julia/packages/DiffEqBase/8usQ9/src/diffeqfunction.jl:106
 [6] initialize!(::OrdinaryDiffEq.ODEIntegrator{Tsit5,Array{Float64,2},Float64,Nothing,Float64,Float64,Float64,Array{Array{Float64,2},1},ODESolution{Float64,3,Array{Array{Float64,2},1},Nothing,Nothing,Array{Float64,1},Array{Array{Array{Float64,2},1},1},ODEProblem{Array{Float64,2},Tuple{Float64,Float64},false,Nothing,ODEFunction{false,getfield(Main, Symbol("##9#10")),UniformScaling{Bool},Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing},Nothing,DiffEqBase.StandardODEProblem},Tsit5,OrdinaryDiffEq.InterpolationData{ODEFunction{false,getfield(Main, Symbol("##9#10")),UniformScaling{Bool},Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing},Array{Array{Float64,2},1},Array{Float64,1},Array{Array{Array{Float64,2},1},1},OrdinaryDiffEq.Tsit5ConstantCache{Float64,Float64}}},ODEFunction{false,getfield(Main, Symbol("##9#10")),UniformScaling{Bool},Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing},OrdinaryDiffEq.Tsit5ConstantCache{Float64,Float64},OrdinaryDiffEq.DEOptions{Float64,Float64,Float64,Float64,typeof(DiffEqBase.ODE_DEFAULT_NORM),typeof(opnorm),CallbackSet{Tuple{},Tuple{DiscreteCallback{getfield(DiffEqCallbacks, Symbol("##28#29")),DiffEqCallbacks.SavingAffect{getfield(Main, Symbol("##11#12")),Float64,Tuple{Float64,Float64},DataStructures.BinaryHeap{Float64,DataStructures.LessThan},Array{Float64,1}},typeof(DiffEqCallbacks.saving_initialize)}}},typeof(DiffEqBase.ODE_DEFAULT_ISOUTOFDOMAIN),typeof(DiffEqBase.ODE_DEFAULT_PROG_MESSAGE),typeof(DiffEqBase.ODE_DEFAULT_UNSTABLE_CHECK),DataStructures.BinaryHeap{Float64,DataStructures.LessThan},DataStructures.BinaryHeap{Float64,DataStructures.LessThan},Nothing,Nothing,Int64,Array{Float64,1},Array{Float64,1},Array{Float64,1}},Array{Float64,2},Float64}, ::OrdinaryDiffEq.Tsit5ConstantCache{Float64,Float64}) at /Users/karrasch/.julia/packages/OrdinaryDiffEq/SXL9q/src/perform_step/low_order_rk_perform_step.jl:524
 [7] #__init#205(::Int64, ::Array{Float64,1}, ::Array{Float64,1}, ::Array{Float64,1}, ::Nothing, ::Bool, ::Nothing, ::Bool, ::Bool, ::Bool, ::DiscreteCallback{getfield(DiffEqCallbacks, Symbol("##28#29")),DiffEqCallbacks.SavingAffect{getfield(Main, Symbol("##11#12")),Float64,Tuple{Float64,Float64},DataStructures.BinaryHeap{Float64,DataStructures.LessThan},Array{Float64,1}},typeof(DiffEqCallbacks.saving_initialize)}, ::Bool, ::Bool, ::Float64, ::Bool, ::Rational{Int64}, ::Nothing, ::Nothing, ::Int64, ::Rational{Int64}, ::Int64, ::Int64, ::Rational{Int64}, ::Bool, ::Int64, ::Nothing, ::Nothing, ::Int64, ::Float64, ::Float64, ::typeof(DiffEqBase.ODE_DEFAULT_NORM), ::typeof(opnorm), ::typeof(DiffEqBase.ODE_DEFAULT_ISOUTOFDOMAIN), ::typeof(DiffEqBase.ODE_DEFAULT_UNSTABLE_CHECK), ::Bool, ::Bool, ::Bool, ::Bool, ::Bool, ::Bool, ::Bool, ::Bool, ::Int64, ::String, ::typeof(DiffEqBase.ODE_DEFAULT_PROG_MESSAGE), ::Nothing, ::Bool, ::Bool, ::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}, ::typeof(DiffEqBase.__init), ::ODEProblem{Array{Float64,2},Tuple{Float64,Float64},false,Nothing,ODEFunction{false,getfield(Main, Symbol("##9#10")),UniformScaling{Bool},Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing},Nothing,DiffEqBase.StandardODEProblem}, ::Tsit5, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Type{Val{true}}) at /Users/karrasch/.julia/packages/OrdinaryDiffEq/SXL9q/src/solve.jl:325
 [8] (::getfield(DiffEqBase, Symbol("#kw##__init")))(::NamedTuple{(:callback,),Tuple{DiscreteCallback{getfield(DiffEqCallbacks, Symbol("##28#29")),DiffEqCallbacks.SavingAffect{getfield(Main, Symbol("##11#12")),Float64,Tuple{Float64,Float64},DataStructures.BinaryHeap{Float64,DataStructures.LessThan},Array{Float64,1}},typeof(DiffEqCallbacks.saving_initialize)}}}, ::typeof(DiffEqBase.__init), ::ODEProblem{Array{Float64,2},Tuple{Float64,Float64},false,Nothing,ODEFunction{false,getfield(Main, Symbol("##9#10")),UniformScaling{Bool},Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing},Nothing,DiffEqBase.StandardODEProblem}, ::Tsit5, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Type{Val{true}}) at ./none:0
 [9] #__solve#204(::Base.Iterators.Pairs{Symbol,DiscreteCallback{getfield(DiffEqCallbacks, Symbol("##28#29")),DiffEqCallbacks.SavingAffect{getfield(Main, Symbol("##11#12")),Float64,Tuple{Float64,Float64},DataStructures.BinaryHeap{Float64,DataStructures.LessThan},Array{Float64,1}},typeof(DiffEqCallbacks.saving_initialize)},Tuple{Symbol},NamedTuple{(:callback,),Tuple{DiscreteCallback{getfield(DiffEqCallbacks, Symbol("##28#29")),DiffEqCallbacks.SavingAffect{getfield(Main, Symbol("##11#12")),Float64,Tuple{Float64,Float64},DataStructures.BinaryHeap{Float64,DataStructures.LessThan},Array{Float64,1}},typeof(DiffEqCallbacks.saving_initialize)}}}}, ::Function, ::ODEProblem{Array{Float64,2},Tuple{Float64,Float64},false,Nothing,ODEFunction{false,getfield(Main, Symbol("##9#10")),UniformScaling{Bool},Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing},Nothing,DiffEqBase.StandardODEProblem}, ::Tsit5, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Type{Val{true}}) at /Users/karrasch/.julia/packages/OrdinaryDiffEq/SXL9q/src/solve.jl:6
 [10] #__solve at ./none:0 [inlined] (repeats 5 times)
 [11] #solve#442(::Base.Iterators.Pairs{Symbol,DiscreteCallback{getfield(DiffEqCallbacks, Symbol("##28#29")),DiffEqCallbacks.SavingAffect{getfield(Main, Symbol("##11#12")),Float64,Tuple{Float64,Float64},DataStructures.BinaryHeap{Float64,DataStructures.LessThan},Array{Float64,1}},typeof(DiffEqCallbacks.saving_initialize)},Tuple{Symbol},NamedTuple{(:callback,),Tuple{DiscreteCallback{getfield(DiffEqCallbacks, Symbol("##28#29")),DiffEqCallbacks.SavingAffect{getfield(Main, Symbol("##11#12")),Float64,Tuple{Float64,Float64},DataStructures.BinaryHeap{Float64,DataStructures.LessThan},Array{Float64,1}},typeof(DiffEqCallbacks.saving_initialize)}}}}, ::Function, ::ODEProblem{Array{Float64,2},Tuple{Float64,Float64},false,Nothing,ODEFunction{false,getfield(Main, Symbol("##9#10")),UniformScaling{Bool},Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing},Nothing,DiffEqBase.StandardODEProblem}, ::Tsit5) at /Users/karrasch/.julia/packages/DiffEqBase/8usQ9/src/solve.jl:39
 [12] (::getfield(DiffEqBase, Symbol("#kw##solve")))(::NamedTuple{(:callback,),Tuple{DiscreteCallback{getfield(DiffEqCallbacks, Symbol("##28#29")),DiffEqCallbacks.SavingAffect{getfield(Main, Symbol("##11#12")),Float64,Tuple{Float64,Float64},DataStructures.BinaryHeap{Float64,DataStructures.LessThan},Array{Float64,1}},typeof(DiffEqCallbacks.saving_initialize)}}}, ::typeof(solve), ::ODEProblem{Array{Float64,2},Tuple{Float64,Float64},false,Nothing,ODEFunction{false,getfield(Main, Symbol("##9#10")),UniformScaling{Bool},Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing},Nothing,DiffEqBase.StandardODEProblem}, ::Tsit5) at ./none:0
 [13] top-level scope at none:0

[dkarrasch]

I just saw that the parameter p in the second line was also missing. That fixes the issue.

EDIT: Well, I guess what remains is to fix the docs.