shortName before FPWD creates invalid link

[ProgramMax]

Description of problem

We have published PNG 3rd Edition under the shortName png-3.
We are currently working on 4th Edition (png-4).
When we add 'shortName: "png-4"' to the respecConfig, it creates:
"Latest published version:
https://www.w3.org/TR/png-4/"

But because we haven't yet hit First Public Working Draft, that link is invalid.

URL to affected spec or repo:

https://w3c.github.io/png

What happened (e.g., it crashed)?:

404

Expected behavior (e.g., it shouldn't crash):

Perhaps Respec should see that we aren't yet to FPWD and link to https://www.w3.org/TR/png/ instead?

[ProgramMax]

Tagging @svgeesus so he's aware.

[svgeesus]

Fixed in the png repo (by deleting the shortname) but perhaps could be better documented?