Need help in error display

Hello,
The user verification in register works good.

After registration, I directly go to login and when I enter email only and put password field blank, the error display " Verify your email first" but when I enter value in both fields it display error "Invalid password or username".

I want it to exchange this error situation, how can I do that.

Please help.
Website Link:
https://hk2.d1e.myftpupload.com/