Pass -fno-sanitize-recover=all to make all UBSan detections fatal

From the clang docs:

> By default, non-fatal checks are those enabled by UndefinedBehaviorSanitizer, except for -fsanitize=return and -fsanitize=unreachable.

.github/workflows/ci.yml

@@ -28,7 +28,7 @@ jobs:
       with:
         submodules: recursive
     - name: Build
-      run: CMAKE_OPTIONS="-DCMAKE_C_FLAGS=-fsanitize=address,undefined" make
+      run: CMAKE_OPTIONS="-DCMAKE_C_FLAGS=-fsanitize=address,undefined -fno-sanitize-recover=all" make
     - name: Test
       run: make test
     - name: Test with Aggressive GC