Structural simplify broken for SDEs

[TorkelE]

As the title says. This is required when e.g. combing and SDE with an algebraic equation. Example:

using ModelingToolkit
using ModelingToolkit: t_nounits as t, D_nounits as D

# Define some variables
@parameters p d 
@variables X(t)
eqs = [D(X) ~ p - d*X]
noise_eqs = [sqrt(p), sqrt(p - d*X)]

@named ssys = SDESystem(eqs, noise_eqs, t, [X], [p, d])
structural_simplify(ssys)

gives

ERROR: This should never happen. Trying to set DataType with @NamedTuple{substitutions::ModelingToolkit.Substitutions}.
Stacktrace:
  [1] error(s::String)
    @ Base ./error.jl:35
  [2] #s300#199
    @ ~/.julia/dev/ModelingToolkit/src/systems/abstractsystem.jl:629 [inlined]
  [3] var"#s300#199"(::Any, obj::Any, patch::Any)
    @ ModelingToolkit ./none:0
  [4] (::Core.GeneratedFunctionStub)(::UInt64, ::LineNumberNode, ::Any, ::Vararg{Any})
    @ Core ./boot.jl:602
  [5] set
    @ ~/.julia/packages/Setfield/PdKfV/src/lens.jl:122 [inlined]
  [6] macro expansion
    @ ~/.julia/packages/Setfield/PdKfV/src/sugar.jl:197 [inlined]
  [7] tearing_reassemble(state::TearingState{…}, var_eq_matching::ModelingToolkit.BipartiteGraphs.Matching{…}, full_var_eq_matching::Nothing; simplify::Bool, mm::ModelingToolkit.SparseMatrixCLIL{…})
    @ ModelingToolkit.StructuralTransformations ~/.julia/dev/ModelingToolkit/src/structural_transformation/symbolics_tearing.jl:564
  [8] tearing_reassemble (repeats 2 times)
    @ ~/.julia/dev/ModelingToolkit/src/structural_transformation/symbolics_tearing.jl:220 [inlined]
  [9] #dummy_derivative#126
    @ ~/.julia/dev/ModelingToolkit/src/structural_transformation/symbolics_tearing.jl:648 [inlined]
 [10] _structural_simplify!(state::TearingState{…}, io::Nothing; simplify::Bool, check_consistency::Bool, fully_determined::Bool, warn_initialize_determined::Bool, dummy_derivative::Bool, kwargs::@Kwargs{})
    @ ModelingToolkit ~/.julia/dev/ModelingToolkit/src/systems/systemstructure.jl:692
 [11] _structural_simplify!
    @ ~/.julia/dev/ModelingToolkit/src/systems/systemstructure.jl:672 [inlined]
 [12] #structural_simplify!#1069
    @ ~/.julia/dev/ModelingToolkit/src/systems/systemstructure.jl:665 [inlined]
 [13] __structural_simplify(sys::SDESystem, io::Nothing; simplify::Bool, kwargs::@Kwargs{})
    @ ModelingToolkit ~/.julia/dev/ModelingToolkit/src/systems/systems.jl:76
 [14] __structural_simplify
    @ ~/.julia/dev/ModelingToolkit/src/systems/systems.jl:57 [inlined]
 [15] structural_simplify(sys::SDESystem, io::Nothing; simplify::Bool, split::Bool, kwargs::@Kwargs{})
    @ ModelingToolkit ~/.julia/dev/ModelingToolkit/src/systems/systems.jl:22
 [16] structural_simplify
    @ ~/.julia/dev/ModelingToolkit/src/systems/systems.jl:19 [inlined]
 [17] structural_simplify(sys::SDESystem)
    @ ModelingToolkit ~/.julia/dev/ModelingToolkit/src/systems/systems.jl:19
 [18] top-level scope
    @ ~/Desktop/Julia Playground/Environment - Catalyst test/test_playground.jl:72
Some type information was truncated. Use `show(err)` to see complete types.

The corresponding code, but for making and ODE, works fine:

using ModelingToolkit, StochasticDiffEq
using ModelingToolkit: t_nounits as t, D_nounits as D

# Define some variables
@parameters p d 
@variables X(t)
eqs = [D(X) ~ p - d*X]
noise_eqs = [sqrt(p), sqrt(p - d*X)]

@named osys = ODESystem(eqs, t, [X], [p, d])
structural_simplify(osys)

[oameye]

Having the same problem

using ModelingToolkit
using ModelingToolkit: t_nounits as t, D_nounits as D
@parameters begin
    α = 1.0 # parameters
    λ = 0.02
    ω = 1.0
    ω0 = 1.0
    γ = 0.005
end
@variables x(t) = 0.0
eqs = [D(D(x)) ~ -(ω0^2 - λ*cos(2*ω*t))*x - α*x^3 - γ*D(x)]

Ttr = 30_000.0
T = 100_000.0
tspan = (0.0, Ttr + T)
times = range((Ttr, Ttr + T)..., step=1)
@mtkbuild model = ODESystem(eqs, t; tspan=tspan)

@mtkbuild sdesystem = SDESystem(model, [0.0,0.0])

[oameye]

Forgot, we had to use System:

@parameters begin
    α = 1.0 # parameters
    λ = 0.02
    ω = 1.0
    ω0 = 1.0
    γ = 0.005
end
@brownian β
@variables x(t) = 0.0 x_t(t) = 0.0
eqs = [ 
    D(x) ~ x_t + β,
    D(x_t) ~ -(ω0^2 - λ*cos(2*ω*t))*x - α*x^3 - γ*x_t + β,
]

Ttr = 30_000.0
T = 100_000.0
tspan = (0.0, Ttr + T)
times = range((Ttr, Ttr + T)..., step=1)
@mtkbuild model = System(eqs, t; tspan=tspan)

typeof(model)

[ChrisRackauckas]

I believe this was fixed with the change to System, and pointed out in the other issue that is now closed?