Node js Passport js if email exist the error displayed. but the username exist error doesn't display

Few days ago i asked a question about node js and passport js. [Here it is]{node js passport js username field error and password field error doesn't display when the form submiting} i already solved that issue and but it has another error. when i submit the form if that email is exist the user can see the error. but if username also exist the error does not display. can you guys anybody help me to why is this happening and let me know how to fix it

thank you

via Chathura Buddika