SCIP OA poisson with tailed cardinality

[hannahtro]

There seems to be a problem with the SCIP wrapper which occurs in the tailed_cardinality_poisson.jl example on the ablation branch.
The termination status of SCIP OA is INFEASIBLE for all tested instances, even though Boscia finds a solution.

When printing the model in enforce_epigraph() or checking is_linear_feasible(), the following error is thrown:

KeyError: key Ptr{Nothing} @0x0000000007e7f780 not found
Stacktrace:
  [1] getindex
    @ ./dict.jl:482 [inlined]
  [2] ref
    @ ~/.julia/packages/SCIP/Qi9Jw/src/MOI_wrapper.jl:74 [inlined]
  [3] #53
    @ ./none:0 [inlined]
  [4] iterate
    @ ./generator.jl:47 [inlined]
  [5] collect(itr::Base.Generator{UnitRange{Int64}, SCIP.var"#53#54"{SCIP.Optimizer, Vector{Float64}, Vector{Ptr{Nothing}}}})
    @ Base ./array.jl:678
  [6] get(o::SCIP.Optimizer, #unused#::MathOptInterface.ConstraintFunction, ci::MathOptInterface.ConstraintIndex{MathOptInterface.ScalarAffineFunction{Float64}, MathOptInterface.LessThan{Float64}})
    @ SCIP ~/.julia/packages/SCIP/BUSgq/src/MOI_wrapper/linear_constraints.jl:46
  [7] is_linear_feasible_subroutine(o::SCIP.Optimizer, #unused#::Type{MathOptInterface.ScalarAffineFunction{Float64}}, #unused#::Type{MathOptInterface.LessThan{Float64}}, valvar::Function)
    @ Boscia ~/git/ZIB/Boscia.jl/src/problem.jl:158
  [8] is_linear_feasible(o::SCIP.Optimizer, v::Vector{Float64})
    @ Boscia ~/git/ZIB/Boscia.jl/src/problem.jl:142
  [9] sparse_reg_scip(seed::Int64, dimension::Int64)
    @ Main ~/git/ZIB/Boscia.jl/examples/tailed_cardinality_poisson.jl:116