When cek_call_or_suspend runs a CEK machine for a non-bytecoded Lambda
(e.g. a thunk), _active_vm still pointed to the caller's VM. VmClosure
calls inside the CEK (e.g. hs-wait) would merge their frames with the
caller's VM via call_closure_reuse, causing the VM to skip the CEK's
remaining continuation on resume — producing wrong DOM mutation order
(+active, +active, -active instead of +active, -active, +active).
Fix: swap _active_vm with an empty isolation VM before running the CEK,
restore after. This keeps VmClosure calls on their own frame stack while
preserving js_of_ocaml exception identity (Some path, not None).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
giles
908f4f80d4