[BUG] different JuMP optimizers give different results in `maximum_weight_matching`

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Since Jul 14, 2025.

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Description

bug

Description of bug

In edge cases with poorly defined matching problems (e.g. empty graphs), JuMP behaves differently depending on the solver being used, leading to unhelpful errors instead of returning an empty matching.

How to reproduce

using Graphs
using GraphsMatching
using JuMP: optimizer_with_attributes, MOI
using HiGHS: HiGHS
using Cbc: Cbc
# try either one of these two
opt = optimizer_with_attributes(HiGHS.Optimizer, MOI.Silent() => true)
opt = optimizer_with_attributes(Cbc.Optimizer, MOI.Silent() => true)
g = SimpleGraph{Int64}(0, [Int64[]])
w = [0;;]
maximum_weight_matching(g,opt,w)

Expected behavior

Return an empty matching.

Actual behavior

For some optimizers, an error is raised.

Dominant language
Julia
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