fsm-as-promised: callback error handling

var StateMachine = require('fsm-as-promised'); var assert = require('assert'); var fsm = StateMachine({ initial: 'stopped', events: [{ name: 'start', from: 'stopped', to: 'started' }], callbacks: { onleavestopped: function(opts) { opts.foo = opts.args[0]; return opts; }, onleave: function(opts) { assert(opts.foo === 0); opts.foo++; return opts; }, onstart: function(opts) { assert(opts.foo === 1); opts.foo++; return opts; }, onenterstarted: function(opts) { assert(opts.foo === 2); opts.foo++; return opts; }, onenter: function(opts) { assert(opts.foo === 3); opts.foo++; return opts; }, onenteredstarted: function(opts) { assert(opts.foo === 5); opts.foo++; return opts; }, onentered: function(opts) { assert(opts.foo === 6); opts.foo++; return opts; } } }); fsm.start(0) .catch(function(err) { // what is value of foo? console.log(err); console.log(fsm.current); });