Android back button causes crash after webview used

If I present a webview, remove it, and then press the back button, my app crashes. This is on Android using v1.17.2 scripting in Lua. Anyone any thoughts for a fix or workaround?

It would do for my purposes if I could make the webview completely insensitive to key presses, but it’s hard to see how to do so.

More information: the back button invokes a crash only after a link has been followed within the displayed web site.

This same crash can be repeated from the WebView test distributed with cocos2d-x