A test in the Swift driver Kaitlin Mahar wrote crashes with a null pointer access in bson_init_from_json:
Kaitlin is able to reproduce this using 1.10 but not in 1.9 on macOS. This seems like an issue with the C driver. I couldn't reproduce the crash on Linux, nor from calling bson_init_from_json with the same arguments directly in the C driver. But I have not yet tested the Swift test on macOS yet.