Error handling middleware invoked with null document on save()

[davebaol]

Looks like the fix for issue #5405 breaks error handling middleware on save.
With Mongoose 4.11.2 the 2nd argument of the error handling middleware is indeed null, while it is the document - as expected - with earlier Mongoose versions.

Here's a repro:

const assert = require('assert');
const mongoose = require('mongoose');

const GITHUB_ISSUE = `gh-5466`;

mongoose.connect(`mongodb://localhost:27017/${ GITHUB_ISSUE }`);

var Schema = mongoose.Schema;

describe('Error Handling Middleware', function() {
  before(async function() {
    await mongoose.connection.dropDatabase();
  });

  it('On save res should not be null', function(done) {
    var schema = new Schema({
      name: {
        type: String,
        unique: true
      }
    });
    
    var handleE11000 = function(error, res, next) {
      assert.equal(error.name, 'MongoError');
      assert.equal(error.code, 11000);
      assert.equal(typeof next, 'function');
      assert.notStrictEqual(null, res);  // with mongoose 4.11.1 and below res is the document; with 4.11.2+ is null
      next();
    };

    schema.post('save', handleE11000);

    var Person = mongoose.model('Person', schema);

    var person1 = { name: 'David' };
    var person2 = { name: 'David' };

    Person.on('index', function(error) {
      assert.ifError(error);
      Person.create([person1, person2], function(error) {
        done();
      });
    });
  });
});

Software version:
Node 6.10.2
Mongodb 3.4.1
Mongoose 4.11.2 and above are affected; versions 4.11.1 and below work correctly

[davebaol]

New mongoose 4.11.3 is affected too.

[vkarpov15]

Thanks for pointing this out, will fix ASAP

[davebaol]

@vkarpov15
Thanks, 4.11.4-pre works for me now 👍