Ascync script no output

I have small test
```py
import STPyV8

test = '''
(async() => {
    window = {}
    window.opener = null
    window.opener.location
})()
'''

with STPyV8.JSContext() as ctx:
    ctx.eval(test) # no output
```

without `async` it has expected output `TypeError: Cannot read properties of null (reading 'location')`
