Return Immediately After Failed RAS Conversion

If the RadioAccessSpecifier cannot be built due to
incompatibility, return after sending a response message
to the caller rather than proceeding through the method
which causes an NPE.

Bug: 156786765
Test: manual
Merged-In: Ie829f3909eb217f4382611a80d1d68629f316789
Change-Id: Ie829f3909eb217f4382611a80d1d68629f316789
(cherry picked from commit 36b30ca1)