LLVM does not support filter clauses in exception handling, and we fall back to the JIT.
This is a problem on watchOS, where bitcode does not allow us to fall back to the JIT, and at runtime we end up with assertions/exceptions.
I have a POC of a new linker step that detects filter clauses when building for bitcode, and replaces the corresponding method with an exception, and reports a warning at build time: https://github.com/rolfbjarne/xamarin-macios/commit/f1d46b4b1c94fcea92718d1a4d1321f371ed2482 (this POC detects fault clauses as well, since it was implemented before support for fault clauses was implemented in the mono runtime).
This new linker step runs even if the linker is disabled (although that should be a very rare scenario for watchOS apps, since with the linker disabled the app ends up being too big for the App Store).
One major advantage of the linker step is that it makes debug and release builds behave the same (i.e. no surprises when running the release build)