Model.merge incorrectly merges undefined data

[adamcikado]

Package version

21.4.0

Describe the bug

If you try to pass property with undefined value to .merge method, it actually updates the column value. It should skip the column instead.

class User extends BaseModel {
  @column()
  declare id: number
  
  @column()
  declare username: string | null

  @column()
  declare email: string
}

const user = new User().merge({
  username: 'test',
  email: '[email protected]',
})

// you might receive an object from validator or other source, where object has property, but with undefined value
// which is valid type as merge accepts Partial<>, but any column itself can't have undefined value
user.merge({
  username: 'test2',
  email: undefined, // this value will be actually set
})

user.email // undefined

Reproduction repo

No response