Exit with error code when errors are caught.

[JMTyler]

If errors occur during build, vitreum exits with a success code of 0, which doesn't tell NPM that anything went wrong.

If we change to exit with an error code of 1, it helps to make it a little more clear that something went wrong by giving us the classic NPM error output at the end:

THERE ARE ERRORS
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! [email protected] build: `vitreum --static`
npm ERR! Exit status 1
npm ERR! 
npm ERR! Failed at the [email protected] build script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /Users/jaredtyler/.npm/_logs/2019-05-10T19_07_02_845Z-debug.log

[stolksdorf]

ooo good catch. I think I left a 0 error code in there so that an error during the dev step wouldn't exit out of the nodemon process. Lets add something conditional like:

)(args.targets, args)
	.catch((err)=>{
		console.log(err);
		if(args.dev) return process.exit(0);
		process.exit(1);
	})