[Feature]: Customizable "Webpage not available" screen about capacitor

[Alarson93]

I have found a workaround.

I created a custom WebViewListener that - upon receiving an error - navigates the user to a custom error screen:

class CustomListener(private val activity: WebPortalActivity): WebViewListener() {

    private var hasHandledError = false

    override fun onReceivedError(webView: WebView?) {
        super.onReceivedError(webView)

        // This conditional check prevents multiple errors from triggering multiple navigations
        if (!hasHandledError) {
            hasHandledError = true
            val intent = Intent(activity, WebViewErrorActivity::class.java)
            intent.flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
            activity.startActivity(intent)
        }
    }

}

The custom error screen basically says that something went wrong and it provides a "Return home" button. Tapping the button will navigate the user to a new Bridge Activity, giving them a fresh start without needing to kill the app. If the original issue persists (e.g. they still lack a data connect), the resulting error will simply navigate them back to our custom error screen.

Unfortunately, we cannot give the user any meaningful message about what went wrong because the WebViewListener does not pass the error forward. That's fine for our immediate use case, but I think it would be polite to provide an error in the onReceivedError function of WebViewListener.