Can't get registered user.id in AdonisJS when setting relationships in controller - adonis.js

Question

My code:
users migration
public async up() {
this.schema.createTable(this.tableName, (table) => {
table.increments('id').primary()
table.string('password', 180).nullable()
table.timestamp('created_at', {useTz: true}).notNullable()
table.timestamp('updated_at', {useTz: true}).notNullable()
}
words migration
public async up() {
this.schema.createTable(this.tableName, (table) => {
table.increments('id')
table.timestamp('created_at', {useTz: true})
table.timestamp('updated_at', {useTz: true})
table.integer('user_id').unsigned().references('users.id').onDelete('CASCADE')
})
}
Models/User
#hasMany(() => Word)
public words: HasMany<typeof Word>
Models/Word
#column()
public userId: number
#belongsTo(() => User)
public author: BelongsTo<typeof User>
WordsController
public async store({request, auth}: HttpContextContract) {
const user = auth.user!.id
const data = await request.validate(WordValidator)
const word = await user?.related('words').create(data)
return word
}
When I type auth.user!.id as it is in upper example, it returns this:
"Cannot read properties of undefined (reading 'id')"
I'm registered, it even normally shows my id on other requests (but only get requests).
What can I do, to get registered user id, and set it as userId in word table or what am I doing wrong?
Thanks