ModelingToolkit's structural_simplify fails on LI-cutset simplification

I modified the example on acausal component modelling from ModelingToolkit and I get internal tearing error. In my modification I have a series connected V+R+L+L circuit.

The series connection of inductors/current sources or capacitor/voltage sources is a known problem when solving electrical circuits (see e.g. Chen et al. “A practical regularization technique for modified nodal analysis in large-scale time-domain circuit simulation.” IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems 31.7 (2012): 1031-1040).

Is there any way I can help the structural_simplify in simplifying the system?

using ModelingToolkit, DifferentialEquations

function Pin(;name)
    @variables v(t) i(t)
    ODESystem(Equation[], t, [v, i], [], name=name, defaults=[v=>1.0, i=>1.0])
end
  
function Ground(;name)
    @named g = Pin()
    eqs = [g.v ~ 0]
    ODESystem(eqs, t, [], [], systems=[g], name=name)
end

function Resistor(;name, R = 1.0)
    val = R
    @named p = Pin()
    @named n = Pin()
    @variables v(t)
    @parameters R
    eqs = [
           v ~ p.v - n.v
           0 ~ p.i + n.i
           v ~ p.i * R
          ]
    ODESystem(eqs, t, [v], [R], systems=[p, n], defaults=Dict(R => val), name=name)
end

function Inductor(; name, L = 1.0)
    val = L
    @named p = Pin()
    @named n = Pin()
    @variables v(t) i(t)
    @parameters L
    D = Differential(t)
    eqs = [
           v ~ p.v - n.v
           0 ~ p.i + n.i
           i ~ p.i
           D(i) ~ v / L
          ]
    ODESystem(eqs, t, [v, i], [L], systems=[p, n], defaults=Dict(L => val), name=name)
end

function ConstantVoltage(;name, V = 1.0)
    val = V
    @named p = Pin()
    @named n = Pin()
    @parameters V
    eqs = [
           V ~ p.v - n.v
           0 ~ p.i + n.i
          ]
    ODESystem(eqs, t, [], [V], systems=[p, n], defaults=Dict(V => val), name=name)
end

function connect_pins(ps...)
    eqs = [
           0 ~ sum(p->p.i, ps) # KCL
          ]
    # KVL
    for i in 1:length(ps)-1
        push!(eqs, ps[i].v ~ ps[i+1].v)
    end

    return eqs
end

@parameters t

@named V1 = ConstantVoltage(V=10.0)
@named R1 = Resistor(R=1.0)
@named L1 = Inductor(L=8.0e-9)
@named L2 = Inductor(L=2.0e-9)
@named GND = Ground()

ckt = [
       connect_pins(V1.p, R1.p)
       connect_pins(R1.n, L1.p)
       connect_pins(L1.n, L2.p)
       connect_pins(V1.n, L2.n, GND.g)
      ]

@named ckt_model = ODESystem(ckt, t, systems=[V1, R1, L1, L2, GND])

sys = structural_simplify(ckt_model)

I get this error message when running this code:

ERROR: 

... Internal error in Tearing.jl: vs[1] = 0.

Run with Julia 1.5.4 and Project.toml:

[deps]
DifferentialEquations = "0c46a032-eb83-5123-abaf-570d42b7fbaa"
ModelingToolkit = "961ee093-0014-501f-94e3-6117800e7a78"

Can you post this as an issue instead?

Done: structural_simplify error #931