window.ReactNativeWebView.postMessage is not a function

Bug description:

I’m getting a strange (and relatively rare) exception reported in Sentry.

window.ReactNativeWebView.postMessage is not a function

This exists within a piece of code that explicitly checks if window.ReactNativeWebView is present

if (window.ReactNativeWebView) {
  window.ReactNativeWebView.postMessage(message)
}

To Reproduce:

Because it happens rarely, I can’t give exact reproduction steps.

However:

• two instances were on a Pixel 4 (technically one of these was a Pixel 4a)
• one instance was on an SM-G996U

This appears to be sporadic, even for any given user. I.e. they will experience the bug briefly then it won’t happen again.

Environment:

• OS: Android
• OS version: “Other” (that’s all Sentry gave us)
• react-native version: 0.68.2
• react-native-webview version: v11.22.1

Remarks

• Is it possible that window.ReactNativeWebView needs time to load its properties?
• Is it possible that window.ReactNativeWebView behaves differently depending on the OS/environment the code finds itself executed in? It seems like postMessage is a value instead of a function here.

[kassemitani]

We have the same the issue, reported by Bugsnag for Android devices.

[TheAlmightyBob]

@17Amir17 Based on the limited information thus far, this sounds like an issue with Android’s WebView that this library can’t do anything about. I could be wrong, but we don’t have a repro and the info from @jackkinsella indicates that we are successfully invoking addJavascriptInterface.

I would be somewhat curious if v11.21.2 behave[s|d] any differently, since there was some refactoring in v11.22.0… I would be surprised if that actually makes a difference though, as I don’t think the refactoring would be related, but there were one or two things that unexpectedly broke there.