Invalid code is generated with a MemberExpression against an ObjectExpression.

[nullableVoidPtr]

Proof of concept:

escodegen.generate({
    "type": "MemberExpression",
    "computed": false,
    "object": {
        "type": "ObjectExpression",
        "properties": []
    },
    "property": {
        "type": "Identifier",
        "name": "property"
    }
});

Output:

{}.property

Compared with astring (note the parens around the empty object):

({}).property