before:
    - test if input is valid JSON with `-[NSJSONSerialization
    isValidJSON]` and if not, build our own error.
    - problem: no hints as to why the JSON is invalid

after:
    - attempt direct serialization with `-[NSJSONSerialization
    dataWithJSONObject:options:error:]` and use the library error
    - this can throw an exception in certain failure modes: surround
    the call with try/catch
    - use new functions in SentryError to create an NSError from
    either an NSException or the inout NSError
    - only compile like this for nonrelease builds so we don't incur
    the performance hit of throwing an exception (see apple's docs:
    "For best performance in 64-bit, you should throw exceptions only
    when absolutely necessary.")