Why not follow the original instructions at http://www.angstrom-distribution.org/building-angstrom ?
How could you have followed those instructions? No where does it indicate
to build 'base-image'.
You should be doing something like this instead (from the referenced page):
MACHINE=beaglebone ./oebb.sh bitbake systemd-gnome-image
or whatever machine you want to build for.
n.b. not everyone reads this list using a threaded web interface, so it's
polite to quote at least the portion of the message that you are replying to.
Bitbake should have given you some warning messages upstream. It will also give you the location of its logfile when the error was encountered.
Could you rerun your bitbake and paste its output, including the command you used to invoke it?