Playing around with `DifferentialEquations.jl`

, I ran into a simple corner case. The code corresponds to a trivial ODE, which is a modification of the following (that works just fine).

```
function f(u,p,t)
return p * u
end
u0=0.5
tspan = (0.0,1.0)
prob = ODEProblem(f,u0,tspan,1.01)
sol = solve(prob)
```

If I try to implement an in-place version, however, I get an `InexactError()`

```
function g(du,u,p,t)
du = p*u
end
u0=0.5
tspan = (0.0,1.0)
prob = ODEProblem(g,u0,tspan,1.01)
sol = solve(prob)
```

Here is the full stack trace

```
InexactError()
Stacktrace:
[1] convert(::Type{Int64}, ::Float64) at ./float.jl:679
[2] zeros at ./array.jl:263 [inlined]
[3] zeros at ./array.jl:264 [inlined]
[4] zeros at ./array.jl:266 [inlined]
[5] alg_cache(::OrdinaryDiffEq.Tsit5, ::Float64, ::Float64, ::Type{T} where T, ::Type{T} where T, ::Type{T} where T, ::Float64, ::Float64, ::#g, ::Float64, ::Float64, ::Float64, ::Float64, ::Bool, ::Type{Val{true}}) at /home/jrun/.julia/v0.6/OrdinaryDiffEq/src/caches/low_order_rk_caches.jl:399
[6] #init#1331(::Int64, ::Array{Float64,1}, ::Array{Float64,1}, ::Array{Float64,1}, ::Void, ::Bool, ::Void, ::Bool, ::Bool, ::Void, ::Bool, ::Bool, ::Float64, ::Bool, ::Rational{Int64}, ::Void, ::Void, ::Int64, ::Rational{Int64}, ::Int64, ::Int64, ::Rational{Int64}, ::Bool, ::Int64, ::Rational{Int64}, ::Rational{Int64}, ::Int64, ::Float64, ::Float64, ::DiffEqBase.#ODE_DEFAULT_NORM, ::DiffEqBase.#ODE_DEFAULT_ISOUTOFDOMAIN, ::DiffEqBase.#ODE_DEFAULT_UNSTABLE_CHECK, ::Bool, ::Bool, ::Bool, ::Bool, ::Bool, ::Bool, ::Bool, ::Bool, ::Int64, ::String, ::DiffEqBase.#ODE_DEFAULT_PROG_MESSAGE, ::Void, ::Bool, ::Bool, ::Array{Any,1}, ::DiffEqBase.#init, ::DiffEqBase.ODEProblem{Float64,Float64,true,Float64,#g,Void,Void,UniformScaling{Int64},DiffEqBase.StandardODEProblem}, ::OrdinaryDiffEq.Tsit5, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Type{Val{true}}) at /home/jrun/.julia/v0.6/OrdinaryDiffEq/src/solve.jl:240
[7] (::DiffEqBase.#kw##init)(::Array{Any,1}, ::DiffEqBase.#init, ::DiffEqBase.ODEProblem{Float64,Float64,true,Float64,#g,Void,Void,UniformScaling{Int64},DiffEqBase.StandardODEProblem}, ::OrdinaryDiffEq.Tsit5, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Type{Val{true}}) at ./<missing>:0
[8] #solve#1330(::Array{Any,1}, ::Function, ::DiffEqBase.ODEProblem{Float64,Float64,true,Float64,#g,Void,Void,UniformScaling{Int64},DiffEqBase.StandardODEProblem}, ::OrdinaryDiffEq.Tsit5, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Type{Val{true}}) at /home/jrun/.julia/v0.6/OrdinaryDiffEq/src/solve.jl:6
[9] (::DiffEqBase.#kw##solve)(::Array{Any,1}, ::DiffEqBase.#solve, ::DiffEqBase.ODEProblem{Float64,Float64,true,Float64,#g,Void,Void,UniformScaling{Int64},DiffEqBase.StandardODEProblem}, ::OrdinaryDiffEq.Tsit5, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Type{Val{true}}) at ./<missing>:0 (repeats 2 times)
[10] #solve#2(::Bool, ::Array{Any,1}, ::Function, ::DiffEqBase.ODEProblem{Float64,Float64,true,Float64,#g,Void,Void,UniformScaling{Int64},DiffEqBase.StandardODEProblem}, ::Void) at /home/jrun/.julia/v0.6/DifferentialEquations/src/default_solve.jl:14
[11] (::DiffEqBase.#kw##solve)(::Array{Any,1}, ::DiffEqBase.#solve, ::DiffEqBase.ODEProblem{Float64,Float64,true,Float64,#g,Void,Void,UniformScaling{Int64},DiffEqBase.StandardODEProblem}, ::Void) at ./<missing>:0
[12] #solve#1(::Bool, ::Array{Any,1}, ::Function, ::DiffEqBase.ODEProblem{Float64,Float64,true,Float64,#g,Void,Void,UniformScaling{Int64},DiffEqBase.StandardODEProblem}) at /home/jrun/.julia/v0.6/DifferentialEquations/src/default_solve.jl:5
[13] solve(::DiffEqBase.ODEProblem{Float64,Float64,true,Float64,#g,Void,Void,UniformScaling{Int64},DiffEqBase.StandardODEProblem}) at /home/jrun/.julia/v0.6/DifferentialEquations/src/default_solve.jl:2
[14] include_string(::String, ::String) at ./loading.jl:522
```

Everything goes through (with minor syntax adjustments) if the ODE is 2-dimensional or higher dimensional.

Any suggestions as to what is the issue here?