Generate correct toString() representation of bytecode in Javascript

I have a very simple task - generate bytecode using typescript traversal. 

for example: 
const g = new Graph().traversal();
const q = g.V().hasLabel("airport").where(__.outE("route").hasId(7753));
const query = new translator("g" as any);
const bytecode = q.getBytecode();
console.log(`Bytecode: ${bytecode.toString()}`);
 
Here is what is generated: 
 
Bytecode: [["V"],["hasLabel","airport"],["where",{"graph":null,"traversalStrategies":null,"bytecode":

{"sourceInstructions":[],"stepInstructions":[["outE","route"],["hasId",7753]]}

,"traversers":null,"sideEffects":null,"_traversalStrategiesPromise":null,"_traversersIteratorIndex":0}]]
 
Looks like it does the first level serialization correct, but the second level isn't properly serialized. 
 
any suggestions what is wrong with this code?