Consider errors in MIR as impossible predicates to empty the body. The ICEs come from elaborating drops or performing state transform in MIR bodies that fail typeck or borrowck. If the body is tainted, replace it with `unreachable`. Fixes https://github.com/rust-lang/rust/issues/122630 Fixes https://github.com/rust-lang/rust/issues/122904 Fixes https://github.com/rust-lang/rust/issues/125185 Fixes https://github.com/rust-lang/rust/issues/139556