EJSON Custom type and Mongo.collection.update

help
1

Hi community.
Can anyone advise me in the following issue

# create a collection
Posts = new Mongo.Collection 'posts'

# define a class
class Topic
	constructor: (value) ->
		{@name, @counts} = value
	typeName: ->
		'topic'
	toJSONValue: ->
		{@name, @counts}
	clone: ->
		new Topic {@name, @counts}
	equals: (other = {}) ->
		other?.name is @name

# register type
EJSON.addType, (value) ->
	new Topic value


# client side
# insert - OK
Posts.insert {text: 'Hello', topic: new Topic('history', 0)}
# update with modifier - OK
Posts.update someId, $set: {text: 'Hello', topic: new Topic('history', 0)}
# update by replace document - OK
Posts.update someId, {text: 'Hello', topic: new Topic('history', 0)}

# server side
# insert - OK
Posts.insert {text: 'Hello', topic: new Topic('history', 0)}
# update with modifier - ERROR: Mongo error: notOkForStore
Posts.update someId, $set: {text: 'Hello', topic: new Topic('history', 0)}
# BUT! update by replace document - OK
Posts.update someId, {text: 'Hello', topic: new Topic('history', 0)}

I cant run update on the server with modifier (like $set), but it works without modifier.
So I dont mind the reason of that behaviour