A mysterious crash with defaults

[hersle]

For reasons I do not understand, the example

using ModelingToolkit

@parameters A1 A2 B1 B2 # it fails with this line uncommented
#@parameters A1 A2=1-A1 B1=A1 B2=A2 # it works with this line uncommented
@variables t x1(t) x2(t)
@named sys = ODESystem([
    x1 ~ B1,
    x2 ~ B2,
], t; defaults = [
    A2 => 1 - A1,
    B1 => A1,
    B2 => A2
])
prob = ODEProblem(structural_simplify(sys), [], (0.0, 1.0), [A1 => 0.3])

mysteriously crashes with

ERROR: UndefRefError: access to undefined reference
Stacktrace:
  [1] getindex
    @ ./essentials.jl:13 [inlined]
  [2] iterate
    @ ./array.jl:945 [inlined]
  [3] narrow_buffer_type(buffer::Vector{Real})
    @ ModelingToolkit ~/.julia/packages/ModelingToolkit/353ne/src/systems/parameter_buffer.jl:196
  [4] _broadcast_getindex_evalf
    @ ./broadcast.jl:709 [inlined]
  [5] _broadcast_getindex
    @ ./broadcast.jl:682 [inlined]
  [6] #31
    @ ./broadcast.jl:1118 [inlined]
  [7] ntuple
    @ ./ntuple.jl:48 [inlined]
  [8] copy
    @ ./broadcast.jl:1118 [inlined]
  [9] materialize(bc::Base.Broadcast.Broadcasted{…})
    @ Base.Broadcast ./broadcast.jl:903
 [10] ModelingToolkit.MTKParameters(sys::ODESystem, p::Dict{…}, u0::Vector{…}; tofloat::Bool, use_union::Bool)
    @ ModelingToolkit ~/.julia/packages/ModelingToolkit/353ne/src/systems/parameter_buffer.jl:159
 [11] ModelingToolkit.MTKParameters(sys::ODESystem, p::Dict{SymbolicUtils.BasicSymbolic{Real}, Float64}, u0::Vector{Any})
    @ ModelingToolkit ~/.julia/packages/ModelingToolkit/353ne/src/systems/parameter_buffer.jl:16
 [12] process_DEProblem(constructor::Type, sys::ODESystem, u0map::Vector{…}, parammap::Vector{…}; implicit_dae::Bool, du0map::Nothing, version::Nothing, tgrad::Bool, jac::Bool, checkbounds::Bool, sparse::Bool, simplify::Bool, linenumbers::Bool, parallel::Symbolics.SerialForm, eval_expression::Bool, use_union::Bool, tofloat::Bool, symbolic_u0::Bool, u0_constructor::typeof(identity), guesses::Dict{…}, t::Float64, warn_initialize_determined::Bool, build_initializeprob::Bool, initialization_eqs::Vector{…}, kwargs::@Kwargs{…})
    @ ModelingToolkit ~/.julia/packages/ModelingToolkit/353ne/src/systems/diffeqs/abstractodesystem.jl:875
 [13] process_DEProblem
    @ ~/.julia/packages/ModelingToolkit/353ne/src/systems/diffeqs/abstractodesystem.jl:766 [inlined]
 [14] (ODEProblem{…})(sys::ODESystem, u0map::Vector{…}, tspan::Tuple{…}, parammap::Vector{…}; callback::Nothing, check_length::Bool, warn_initialize_determined::Bool, kwargs::@Kwargs{})
    @ ModelingToolkit ~/.julia/packages/ModelingToolkit/353ne/src/systems/diffeqs/abstractodesystem.jl:1018
 [15] (ODEProblem{…})(sys::ODESystem, u0map::Vector{…}, tspan::Tuple{…}, parammap::Vector{…})
    @ ModelingToolkit ~/.julia/packages/ModelingToolkit/353ne/src/systems/diffeqs/abstractodesystem.jl:1008
 [16] (ODEProblem{true})(::ODESystem, ::Vector{Any}, ::Vararg{Any}; kwargs::@Kwargs{})
    @ ModelingToolkit ~/.julia/packages/ModelingToolkit/353ne/src/systems/diffeqs/abstractodesystem.jl:995
 [17] (ODEProblem{true})(::ODESystem, ::Vector{Any}, ::Vararg{Any})
    @ ModelingToolkit ~/.julia/packages/ModelingToolkit/353ne/src/systems/diffeqs/abstractodesystem.jl:994
 [18] ODEProblem(::ODESystem, ::Vector{Any}, ::Vararg{Any}; kwargs::@Kwargs{})
    @ ModelingToolkit ~/.julia/packages/ModelingToolkit/353ne/src/systems/diffeqs/abstractodesystem.jl:984
 [19] ODEProblem(::ODESystem, ::Vector{Any}, ::Vararg{Any})
    @ ModelingToolkit ~/.julia/packages/ModelingToolkit/353ne/src/systems/diffeqs/abstractodesystem.jl:983
 [20] top-level scope
    @ REPL[16]:1
Some type information was truncated. Use `show(err)` to see complete types.

This is with ] status

  [0c46a032] DifferentialEquations v7.13.0
  [961ee093] ModelingToolkit v9.19.0
  [1dea7af3] OrdinaryDiffEq v6.84.0
  [2efcf032] SymbolicIndexingInterface v0.3.22
  [d1185830] SymbolicUtils v2.0.2
  [0c5d862f] Symbolics v5.30.3
  ...

Is anyone able to reproduce this?