Tell us about your environment

• Node Version: v12.16.2
• comment-json Version: 3.0.2

Please show your use case / code slices / code link that could reproduce the issue

const C = require("comment-json");
const o = C.parse(`{
  "test": true // hello
}`);
o.newProperty = true;
console.log(C.stringify(o, null, 2));

Actual output:

{
  "test": true // hello
  ,
  "newProperty": true
}

What did you expect to happen?

{
  "test": true, // hello
  "newProperty": true
}

Are you willing to submit a pull request to fix this bug?

With help, sure! Not sure how easy this is to fix.