Or do the sensible thing and just drop the announcement and log the problem.
Which is exactly what an RFC7606 compliant device will do for an unknown path attribute.
o Treat-as-withdraw: In this approach, the UPDATE message containing
the path attribute in question MUST be treated as though all
contained routes had been withdrawn just as if they had been
listed in the WITHDRAWN ROUTES field (or in the MP_UNREACH_NLRI
attribute if appropriate) of the UPDATE message, thus causing them
to be removed from the Adj-RIB-In according to the procedures of
[RFC4271].
d. If any of the well-known mandatory attributes are not present in
an UPDATE message, then "treat-as-withdraw" MUST be used. (Note
that [RFC4760] reclassifies NEXT_HOP as what is effectively
discretionary.)
e. "Treat-as-withdraw" MUST be used for the cases that specify a
session reset and involve any of the attributes ORIGIN, AS_PATH,
NEXT_HOP, MULTI_EXIT_DISC, or LOCAL_PREF.