JET 0.11 surfaces latent errors in Surrogates (report_package)

[ChrisRackauckas-Claude]

The QA group now runs whole-package JET via SciMLTesting.run_qa (JET.test_package(Surrogates; target_modules=(Surrogates,), mode=:typo)). On JET 0.10 (the version CI's QA lanes resolve on both lts/1.10 and 1/1.12) this passes clean. On JET 0.11.5 (newer, stronger analysis) JET.report_package(Surrogates; target_modules=(Surrogates,)) surfaces 22 reports / 9 distinct top-level error sites, several of which look like genuine latent bugs:

• src/Sampling.jl:60 — Surrogates.ZERO_SAMPLES_MESSAGE is not defined (referenced but never bound).
• src/Wendland.jl (precompile path) — Surrogates.Wendand is not defined (typo for Wendland).
• src/GEKPLS.jl:558/566 — local variable r may be undefined.
• src/Optimization.jl — local variable counter may be undefined; Surrogates.x_new not defined.
• src/VariableFidelity.jl — low_fid_surr may be undefined; several kwcall no-matching-method reports for NeuralSurrogate / XGBoostSurrogate extension constructors; (::Nothing)(::Any) calls.

The QA env pins JET = "0.9, 0.10" for now so the QA lane stays green on the JET version CI actually resolves; this issue tracks fixing the underlying findings and then widening the JET compat to include 0.11.

Full report_package output (JET 0.11.5, Julia 1.12):

[1]  UndefVarErrorReport(`Surrogates.ZERO_SAMPLES_MESSAGE` is not defined)            src/Sampling.jl:60
[2]  UndefVarErrorReport(local variable `r` may be undefined)                          src/GEKPLS.jl
[3]  UndefVarErrorReport(local variable `r` may be undefined)                          src/GEKPLS.jl
[4]  MethodErrorReport sample(::Int64, ::Number, ::AbstractVector, ::SamplingAlgorithm)
[5]  MethodErrorReport sample(::Int64, ::Number, ::Tuple{Vararg{T}}, ::SamplingAlgorithm)
[6-9] MethodErrorReport (::Colon)(::Int64, ::AbstractUnitRange)  (num_new_samples)     src/Optimization.jl
[10] UndefVarErrorReport(local variable `counter` may be undefined)
[11-12] UndefVarErrorReport(`Surrogates.x_new` is not defined)
[13] UndefVarErrorReport(local variable `counter` may be undefined)
[14] MethodErrorReport kwcall NeuralSurrogate (model/loss/opt/n_epochs)                src/VariableFidelity.jl
[15] MethodErrorReport kwcall XGBoostSurrogate (num_round)                             src/VariableFidelity.jl
[16] UndefVarErrorReport(local variable `low_fid_surr` is not defined)
[17-18] MethodErrorReport (::Nothing)(::Any)  (low_fid_surr)
[19] MethodErrorReport kwcall NeuralSurrogate (model/loss/opt/n_epochs)
[20] MethodErrorReport kwcall XGBoostSurrogate (num_round)
[21] UndefVarErrorReport(`Surrogates.Wendand` is not defined)                          src/Wendland.jl (typo for Wendland)
[22] MethodErrorReport /(::Float64, ::Type)                                            (nt)