fix:  Add missing export StackElement
fix:  Add missing export StackElement

Signed-off-by: Gordon Smith <08e1f79d4e30392bc0547075fd86e18f1dc49c1e@gmail.com>

hpcc-systems/hpcc-js-wasm,hpcc-systems/hpcc-js-wasm,hpcc-systems/hpcc-js-wasm,hpcc-systems/hpcc-js-wasm,hpcc-systems/hpcc-js-wasm,hpcc-systems/hpcc-js-wasm