Unexpected token 'if'

[wangxdmm]

 // const code = `return {'if': 1};`;// ok
    const code = `return {if: 1};`; // error Unexpected token 'if': {if: 1}
    const sandbox = new Sandbox();
    const exec = sandbox.compile(code);
    exec().run()

Everything works perfectly up to 0.8.28, but as soon as I upgrade past 0.8.28, return {if: 1} starts throwing an error.