null command and parameter expansion for "Display error if null or unset"

[Poor Yorick]

The following line does not perform the "echo" command.

: ${FAKEVAR?} || echo hello

This seems inconsistent, since the return status is set to one, not to mention 
that the null command is documented to return a zero exit code.  It would be a 
convenient and concise syntax for acting on unset variables.

-- 
Poor Yorick