JsonToken::asObject() odd behavior with empty objects

[pezcode]

JsonToken::asObject() behaves in interesting ways given the following json:

{
}

In our code, we're getting access violation exceptions due to bogus pointer values, and the attached patch to UtilityJsonTest produces an odd error message:

Utility::JsonToken::find(): token is a parsed Utility::JsonToken::Type::Number, expected a parsed object

corrade-14-15-21.patch

[mosra]

Argh, that was a silly unhandled corner case, especially with the comment next to it saying that "it should never happen". Sorry about that. Most of the uses of find() or operator[]() happen directly on a JsonToken, performing that on a JsonObjectView / JsonArrayView is a rather rare scenario which probably explains I never encountered this case so far.

Fixed in fa7fa30, and although I managed to find a case where this would produce a similar assertion (and another case where it'd just silently produce a wrong result), your patch triggered a plain segfault on a null pointer in my case, not the error you reported.

[pezcode]

Thank you for the quick fix ☺️ Much appreciated!