Unhandled errors when parent opens up inside Facebook or Instagram browsers: null is not an object (evaluating 'e.contentWindow.postMessage')

[J-Gonzalez]

Our Sentry is littered with thousands of errors on the parent application stating: Unhandled null is not an object (evaluating 'e.contentWindow.postMessage')

As far as we can tell, the parent and child are communicating with no issues (child has props passed from parent, and child calls oncomplete prop from parent and parent responds without issue).

We're not really sure how to dig into this but wondering if anyone else has seen this.