TRY_BLOCK_ERROR and exit status

[Bart Schaefer <schaefer@brasslantern.com>]

On Nov 23,  7:08pm, Mikael Magnusson wrote:
}
} % { $(< foo) } always { TRY_BLOCK_ERROR=0 }; echo hello
} zsh: no such file or directory: foo
} hello
} 
} However, I'm not sure how to
} make the construct return false when it failed with a fatal error.

Arguably a fatal error should set both errflag and lastval nonzero, but
that might require a lot of tiny changes all over the place ... on the
other hand I think always+TRY_BLOCK_ERROR is the only way lastval can
still be examined after errflag has been set, so maybe it would suffice
to handle this there?

What should the value of lastval ($?) be in this circumstance?