Previously in v9, we deprecated the pattern of undecorated base classes
that rely on Angular features. We ran a migration for this in version 9
and will run the same on in version 10 again.
To ensure that projects do not regress and start using the unsupported
pattern again, we report an error in ngtsc if such undecorated classes
are discovered.
We keep the compatibility code enabled in ngcc so that libraries
can be still be consumed, even if they have not been migrated yet.
Resolves FW-2130.
PR Close#36921
4c92cf43cf