If you want to apply conditional validation on 'Number' or 'Even Number', then you need to add 'Type' input as 'Even'
{{userForm.controls?.type?.errors?.even.message}}
If you want to apply conditional validation on 'Even Number' then you need to add 'Type' input as 'Even'.
Conditional Expression with type 'string'
{{userForm.controls?.evenNumber?.errors?.even.message}}