1Example-Broken-ES6.js

'use strict';

class Test {
  
  constructor(opts = {}) {
    // NOTE: No Semicolon at the end of this line
    const example = JSON.parse(opts.example)

    ({
      id: this.id,
    } = example)
  }
}

2Babel-Compile.js

'use strict';

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

var Test = function Test() {
  var _example;

  var opts = arguments.length <= 0 || arguments[0] === undefined ? {} : arguments[0];

  _classCallCheck(this, Test);

  var example = JSON.parse(opts.example)((_example = example, this.id = _example.id, _example));
};

3Example-Correct-ES6.js

'use strict';

class Test {
  
  constructor(opts = {}) {
    // NOTE: Semicolon at the end of this line
    const example = JSON.parse(opts.example);

    ({
      id: this.id,
    } = example)
  }
}

4Correct.js

'use strict';

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

var Test = function Test() {
  var opts = arguments.length <= 0 || arguments[0] === undefined ? {} : arguments[0];

  _classCallCheck(this, Test);

  var example = JSON.parse(opts.example);

  this.id = example.id;
};

Using ES6 destructuring to assign values to this, you need to be careful how the parenthesis are interpreted!