[BUG] Failing QLS test in the lsm-prototypes-test test suite

[jorisdral]

Describe the bug
A clear and concise description of what the bug is.

To Reproduce

cabal run lsm-prototypes-test -- -p '/ScheduledMerges vs model/' --quickcheck-replay="(SMGen 13641619390099658510 4893538938940949325,19)"

Expected behavior
Tests should pass

Output
The test failure was observed on main here: https://github.com/IntersectMBO/lsm-tree/actions/runs/12954558668/job/36136751315

The following output is produced:

prototype
    ScheduledMerges vs model:            FAIL (0.05s)
      *** Failed! (after 20 tests and 5 shrinks):
      Exception:
        expectCompletedMergingTree: PendingTreeMerge
        CallStack (from HasCallStack):
          error, called at prototypes\ScheduledMerges.hs:1172:31 in lsm-tree-0.1.0.0-inplace-prototypes:ScheduledMerges
          expectCompletedMergingTree, called at prototypes\ScheduledMerges.hs:681:18 in lsm-tree-0.1.0.0-inplace-prototypes:ScheduledMerges
      do var1 <- action $ ANew
         action $ ADelete (unsafeMkGVar var1 OpId) (Right (K 0))
         var5 <- action $ AUnions [unsafeMkGVar var1 OpId,unsafeMkGVar var1 OpId]
         var7 <- action $ AUnions [unsafeMkGVar var5 OpId,unsafeMkGVar var5 OpId]
         action $ ASupplyUnion (unsafeMkGVar var7 OpId) (NonNegative {getNonNegative = 2})
         pure ()
      Use --quickcheck-replay="(SMGen 13641619390099658510 4893538938940949325,19)" to reproduce.
      Use -p '/ScheduledMerges vs model/' to rerun this test only.

Desktop (please complete the following information):

• OS: Windows
• OS version: Windows Server 2022
• GHC: ghc-9.6.4