I think that the reason I asked is that perhaps my subconscious remembered the pain of doing that :) IME, putting extra properties on exceptions is a lot of extra work, so should mostly be done if we think a client might actually need programmatic access to that extra information.

What I'm trying to say is that I'm not sure that putting `PropertyInfo` on `WritablePropertyException` was a good decision. It's only used from tests. Is a better alternative to scan the exception message for the presence of certain, expected strings?

I honestly don't know, as I think there are arguments for and against. Thus, feel free to keep it as is, but also feel free to remove these members if you think it would lead to a better design.