Add missing exit state to composer.try FSM (#44)

Fixes #43

Author: tardieu

composer.js

@@ -342,7 +342,7 @@ function init(__eval__, composition) {
             case 'try':
                 var body = compile(json.body, path + '.body')
                 const handler = chain(compile(json.handler, path + '.handler'), [{ type: 'pass', path }])
-                var fsm = [[{ type: 'try', path }], body].reduce(chain)
+                var fsm = [[{ type: 'try', path }], body, [{ type: 'exit', path }]].reduce(chain)
                 fsm[0].catch = fsm.length
                 fsm.slice(-1)[0].next = handler.length
                 fsm.push(...handler)

test/test.js

@@ -427,6 +427,11 @@ describe('composer', function () {
                         .then(activation => assert.deepEqual(activation.response.result, { message: 'foo' }))
                 })
 
+                it('retain', function () {
+                    return invoke(composer.retain(composer.try(() => ({ p: 4 }))), { n: 3 })
+                        .then(activation => assert.deepEqual(activation.response.result, { params: { n: 3 }, result: { p: 4 } }))
+                })
+
                 it('invalid options', function () {
                     try {
                         invoke(composer.try('isNotOne', 'isNotOne', 'isNotOne'))