abort if any error

[Ray Andrews <rayandrews@xxxxxxxxxxx>]

$ . wonderful_function; wonderful_function

[scrolls off the page ]

But, ooops, my last tweak to the function busted something so it wasn't 
sourced and what ran was the previous version.  Is there some way of 
forcing any script or command line or anything at all to stop 
unconditionally in case of an error on sourcing?  I can't think of a 
situation where I'd not want to stop and fix it.  If it were possible 
I'd bolt that on right at configuration.  I'm betting it can be done.