Function updateExpr

frontend/src/react/components/ExprEditor.tsx:94–101

(
  root: ConditionGroupExpr,
  mutate: (clone: ConditionGroupExpr) => void
)

// Clone root, apply a mutation to the clone, return the clone.
function updateExpr(
  root: ConditionGroupExpr,
  mutate: (clone: ConditionGroupExpr) => void
): ConditionGroupExpr {
  const clone = structuredClone(root);
  mutate(clone);
  return clone;
}

// ============================================================
// Context