odoo version: 11.0

total log:

web.assets_backend.js:1165 Uncaught TypeError: Cannot read property 'views' of undefined
at Class._applyX2ManyChange (web.assets_backend.js:1165)
at Class._applyX2ManyChange (web.assets_backend.js:1171)
at Class._applyChange (web.assets_backend.js:1147)
at Object.<anonymous> (web.assets_common.js:4010)
at Object.<anonymous> (web.assets_common.js:802)
at fire (web.assets_common.js:796)
at Object.add [as done] (web.assets_common.js:797)
at Array.<anonymous> (web.assets_common.js:802)
at Function.each (web.assets_common.js:625)
at Object.<anonymous> (web.assets_common.js:802)

code:

py:

document = fields.Many2many('ir.attachment')

xml:

<field name="document" widget="many2many_binary"/>

detail:

It's ok when i just add or delete a attachment. But when i add attachment after delete one or add two attachments, I will get this error, how i can deal with it?