Errors not emitted properly

Currently, when `deamdify` encounters a syntax error, it `throw`s a regular JavaScript error. That makes it very hard to catch it in the Browserify stream.

Instead, it should emit an `"error"` event on the stream, with the original error as an argument – that is how, for example, [es6ify](https://github.com/thlorenz/es6ify/blob/627e999ff6c2aaeb73f150687513ddb4dfb905e7/index.js#L56) does it.

Is there any specific reason why it's done the way it is currently, or would you be willing to accept a Pull Request?

Start with deamdify's Browserify transform and compare its syntax-error handling with the linked es6ify example. Confirm that a syntax error reaches the stream as an "error" event carrying the original error, rather than being thrown.

Written by the indexing model from the issue text.