关联设置正确会导致未初始化常量

我有一个简单的 many_to_many User 和 Stake UserStake ,所有设置似乎都正确,但结果是 NameError (uninitialized constant User::Stakes) :

#db/schema.rb
ActiveRecord::Schema.define(version: 2020_12_19_070749) do

  create_table "stakes", force: :cascade do |t|
    t.string "address"
    t.datetime "created_at", precision: 6, null: false
    t.datetime "updated_at", precision: 6, null: false
  end

  create_table "user_stakes", force: :cascade do |t|
    t.integer "user_id"
    t.integer "stake_id"
    t.datetime "created_at", precision: 6, null: false
    t.datetime "updated_at", precision: 6, null: false
  end

  create_table "users", force: :cascade do |t|
    t.string "username"
    t.datetime "created_at", precision: 6, null: false
    t.datetime "updated_at", precision: 6, null: false
    t.string "password_digest"
  end

end

#app/models/stake.rb
class Stake < ApplicationRecord
    has_many :active_stakes
    has_many :user_stakes
    has_many :users, through: :user_stakes
end

#app/models/user.rb
class User < ApplicationRecord
    has_many :user_stakes
    has_many :stakes, through: :user_stakes
    
    has_secure_password
end

#app/models/user_stake.rb
class UserStake < ApplicationRecord
    belongs_to :users
    belongs_to :stakes
end

rails c 以下错误 出现:

2.6.3 :019 > s
 => #<Stake id: 310524, address: "stake1u8003gtvhcunzzmy85nfnk6kafd8lks2mykfzf0n4hq4...", created_at: "2020-12-08 12:08:25", updated_at: "2020-12-08 12:08:25"> 
2.6.3 :020 > u
 => #<User id: 21, username: "s324xexd", created_at: "2020-12-19 00:16:31", updated_at: "2020-12-19 00:16:31", password_digest: [FILTERED]> 
2.6.3 :021 > u.stakes << s
Traceback (most recent call last):
        1: from (irb):21
NameError (uninitialized constant User::Stakes)
2.6.3 :022 > u.stakes
Traceback (most recent call last):
        2: from (irb):22
        1: from (irb):22:in `rescue in irb_binding'
NameError (uninitialized constant User::Stakes)