E:\js\node\mooc\app.js:91

            _movie.save(function(err,movie){

                   ^

TypeError: Cannot call method 'save' of null

    at Promise.<anonymous> (E:\js\node\mooc\app.js:91:20)

    at Promise.<anonymous> (E:\js\node\mooc\node_modules\mongoose\node_modules\m

promise\lib\promise.js:177:8)

    at Promise.emit (events.js:95:17)

    at Promise.emit (E:\js\node\mooc\node_modules\mongoose\node_modules\mpromise

\lib\promise.js:84:38)

    at Promise.fulfill (E:\js\node\mooc\node_modules\mongoose\node_modules\mprom

ise\lib\promise.js:97:20)

    at Object.cb (E:\js\node\mooc\node_modules\mongoose\lib\query.js:1146:30)

    at Object._onImmediate (E:\js\node\mooc\node_modules\mongoose\node_modules\m

query\lib\utils.js:137:16)

    at processImmediate [as _immediateCallback] (timers.js:345:15)