Too Long; Didn't Read
In 2016, GitHub user Robert Roskam (raiderrobert) <a href="https://github.com/facebook/react-native/issues/10865" target="_blank">opened an issue</a> on the React Native repository reporting the error <em>“Setting onMessage on a WebView overrides existing values of window.postMessage, but a previous value was defined”</em>. In the two years since then, nothing has been done to resolve it within the internal React Native implementation of WebView.