To follow-up on my previous comment, I was able to work around this "broken state" in aptitude by purging the offending packages with "--force-depends":
dpkg --purge --force-depends "gcc-multilib" dpkg --purge --force-depends "lib32z1-dev" dpkg --purge --force-depends "libc6-dev-x32"
Now, I'm able to use "apt-get" as normal.
Hopefully, this workaround won't cause problems in the future.
To follow-up on my previous comment, I was able to work around this "broken state" in aptitude by purging the offending packages with "--force-depends":
dpkg --purge --force-depends "gcc-multilib"
dpkg --purge --force-depends "lib32z1-dev"
dpkg --purge --force-depends "libc6-dev-x32"
Now, I'm able to use "apt-get" as normal.
Hopefully, this workaround won't cause problems in the future.