:checked handler doesn't raise error when value is blank

[wheeyls]

When there is no value for a model, and no checkbox is checked on page load, this checked handler throws an error.

Making a change to bail out instead of trying to set the value if there is no matching radio to set. I tried to get a spec written for this but running grunt test yielded an error:

running "mocha_phantomjs:all" (mocha_phantomjs) task Test Failed to start mocha: Init timeout Unsafe JavaScript attempt to access frame with URL about:blank from frame with URL file:///Users/mike/code/backbone.epoxy/node_modules/grunt-mocha-phantomjs/node_modules/mocha-phantomjs/lib/mocha-phantomjs.coffee. Domains, protocols and ports must match.

Not sure how up to date your tests are, but I didn't want to monkey with that.