Package: Break on UglifyJS errors in package-1-13

Ref gh-582

Author: mgol

lib/package-1-13.js

@@ -276,8 +276,13 @@ extend( Package.prototype, {
 		}
 
 		this.jsBundle.promise.then( function( js ) {
-			var _banner = banner( pkgJson, jsFileNames, { minify: true } ),
-				minJs = UglifyJS.minify( js ).code;
+			var minJs;
+			var _banner = banner( pkgJson, jsFileNames, { minify: true } );
+			var uglifyResult = UglifyJS.minify( js );
+			if ( uglifyResult.error ) {
+				throw uglifyResult.error;
+			}
+			minJs = uglifyResult.code;
 			callback( null, _banner + minJs );
 		} ).catch( callback );
 	},