I get that. So, in current database systems, how much does this assumption weigh? Or it would be more useful update the message from
psql: FATAL: database "neha" does not exist //Ofcourse, it won't in most cases.
to
psql: FATAL: database "neha" does not exist. Try connecting to an existing database or template database.
Introducing "template database" is probably going to cause more confusion, not less.
<database "neha" does not exist, please provide the name of one that does exist> - the last part seems somewhat self-evident ...
What you really want to say is:
FATAL: blah-blah-blah
HINT: While the database name argument is technically optional you probably want to supply one seeing as how a database with your name, i.e., the default, doesn't exist.