Abort from a .bashrc script

Abort from a .bashrc script

I know the .bashrc script must be run like source .bashrc or . .bashrc so
changes in exports are kept during the session, but i need to abort from
half the bashrc script without exiting the session.
Currently i'm doing a binary search of a point where i issue a command
which assumes the existence of a tty. This is to avoid getting the message
stdin: is not a tty. So the easiest way is to break the execution of the
bashrc script, but i haven't found a way to do so.
How do i abort from half the execution inside the .bashrc script w/o
ending the session? (aka using the exit command)