You should hang out in the developer forum. It's not so much a log as the line number on which the crash occurred and you only get it for published public channels. Go to the Developer Dashboard, Manage My Channels (https://developer.roku.com/developer-channels/channels), and then then View Analytics for the channel in question. You'll probably have to login again and do another Captcha because Roku loves them. Once you're viewing analytics change the dropdown to Channel Health. Then you only have to deal with half a dozen scroll bars. Don't you just love the web team at Roku?
If the channel is still in development and not yet published, you can also do some debugging by using telnet to connect to your roku device.