Apparently you cannot filter based on two parameters in firebase so something similar to "select * from table where email='something' and password ='something' " doesn't work .

So a shitty hack is to create a string to concatenate email and password and store it as a field and validate based on that field.

So basically there is a field in database which is

Sha256("emailid"+_+sha256("password"))

Holy fuck is firebase a uber-AIDS-ridden slimy cunt of a platform. How the fuck is it impossible to give a simple wanking message during deployment of what is going pissingly wrong???
I'd have a lovely smile on my face when I could put the responsible devs at a wall and melt them to ashes with my blazing flamethrower.
3 fucking hours of searching and trying all kinds of shit out and still no clue why the fuck my functions don't appear in their stinking cloud cunthole, I mean console.
Devour a pile of fresh smelly turds, wankers!