`remake` fails with `ERROR: ArgumentError: ... is neither an observed nor an unknown variable.` about modelingtoolkit.jl HOT 2 OPEN

using ModelingToolkit
using ModelingToolkitStandardLibrary: Blocks
gravity = 9.81
gain_u1 = 0.89 / 1.4
d0 = 70
d1 = 17
n0 = 55
@named motor_dynamics = Blocks.FirstOrder(T = 0.001)
x0 = [0.85, 1, π/12, π/2]
@parameters t
@variables  u(t)[1:2]=0
u = collect(u)
@variables y(t)=0.85 v(t)=1 ϕ(t)=π/12 ω(t)=π/2
D = Differential(t)
eqs = [
    D(y) ~ v,
    D(v) ~ -gravity + gain_u1 * cos(ϕ)*(motor_dynamics.output.u + gravity/gain_u1),
    D(ϕ) ~ ω,
    D(ω) ~ -d0 * ϕ - d1 * ω + n0 * u[2],
    motor_dynamics.input.u ~ u[1]
]

@named model = ODESystem(eqs, t; systems=[motor_dynamics])

linearize(model, collect(u), [y, v, ϕ, ω])

julia> linearize(model, collect(u), [y, v, ϕ, ω])
ERROR: ArgumentError: v(t) is neither an observed nor an unknown variable.
Stacktrace:
  [1] build_explicit_observed_function(sys::NonlinearSystem, ts::Vector{…}; inputs::Nothing, expression::Bool, output_type::Type, checkbounds::Bool, drop_expr::typeof(RuntimeGeneratedFunctions.drop_expr), ps::Vector{…}, return_inplace::Bool, op::Type, throw::Bool)
    @ ModelingToolkit ~/.julia/dev/ModelingToolkit/src/systems/diffeqs/odesystem.jl:451
  [2] build_explicit_observed_function(sys::NonlinearSystem, ts::Vector{SymbolicUtils.BasicSymbolic{Real}})
    @ ModelingToolkit ~/.julia/dev/ModelingToolkit/src/systems/diffeqs/odesystem.jl:378
  [3] observed(sys::NonlinearSystem, sym::Vector{SymbolicUtils.BasicSymbolic{Real}})
    @ ModelingToolkit ~/.julia/dev/ModelingToolkit/src/systems/abstractsystem.jl:534
  [4] _getu(sys::NonlinearSystem, ::SymbolicIndexingInterface.NotSymbolic, ::SymbolicIndexingInterface.ScalarSymbolic, sym::Vector{…})
    @ SymbolicIndexingInterface ~/.julia/packages/SymbolicIndexingInterface/A1VUA/src/state_indexing.jl:158
  [5] getu(sys::NonlinearSystem, sym::Vector{SymbolicUtils.BasicSymbolic{Real}})
    @ SymbolicIndexingInterface ~/.julia/packages/SymbolicIndexingInterface/A1VUA/src/state_indexing.jl:32
  [6] linearization_function(sys::ODESystem, inputs::Vector{…}, outputs::Vector{…}; simplify::Bool, initialize::Bool, op::Dict{…}, p::SciMLBase.NullParameters, zero_dummy_der::Bool, initialization_solver_alg::NonlinearSolve.GeneralizedFirstOrderAlgorithm{…}, kwargs::@Kwargs{})
    @ ModelingToolkit ~/.julia/dev/ModelingToolkit/src/systems/abstractsystem.jl:1965
  [7] linearization_function
    @ ~/.julia/dev/ModelingToolkit/src/systems/abstractsystem.jl:1867 [inlined]
  [8] linearize(sys::ODESystem, inputs::Vector{…}, outputs::Vector{…}; op::Dict{…}, t::Float64, allow_input_derivatives::Bool, zero_dummy_der::Bool, kwargs::@Kwargs{})
    @ ModelingToolkit ~/.julia/dev/ModelingToolkit/src/systems/abstractsystem.jl:2325
  [9] linearize(sys::ODESystem, inputs::Vector{Num}, outputs::Vector{Num})
    @ ModelingToolkit ~/.julia/dev/ModelingToolkit/src/systems/abstractsystem.jl:2321
 [10] top-level scope
    @ REPL[3]:1
Some type information was truncated. Use `show(err)` to see complete types.