React Native _weakMap2 error

I just updated to React Native 0.21, but I am getting an error when I require Parse:

var Parse = require('parse/react-native').Parse;

The error I get is:

undefined is not a constructor (evaluating 'new _weakMap2.default()')

I don't believe it has to do with Parse though, as searching the directory, the 'weakMap2' reference is only found inside the react-proxy package.

Has anyone else experienced this error or found a workaround? Thanks!