Handle logging non-JSON-serializable classes in stream slices

[erohmensing]

What

Describe what the change is solving
It helps to add screenshots if it affects the frontend.
Avoid issues like these when trying to log stream slices which contain values that are not serializable. Note that in the case of the linked action, the streamslice class is not a Mapping, so it's not the most valid case here. However, when I implemented that as a TypedDict instead, I ran into the same issue for datetime formats, and I think they're a valid case we should support, hence that being the test case.

How

Describe the solution
When dumping, if a class is not json serializable, dump it as a string.

[maxi297]

This seems like a good idea. Out of curiosity, are there slices today where the value is not JSON serializable?

[maxi297]

Note that you will probably need to run SUB_BUILD=CONNECTORS_BASE ./gradlew format --scan --info --stacktrace

[erohmensing]

Yes! The run I linked is from a connector which defines streamslices as a StreamSlice dataclass (not a dictionary) with the following definition:

@dataclass
class StreamSlice:
    start_date: DateTime
    end_date: DateTime

obviously, this goes against typing to be using a data class instead of a dict or other mapping format - it should still probably be updated to be a TypedDict. However, if you fix that, then you still run into the error because start_date and end_date are pendulum.datetime.DateTimes, which are not json serializable.

I didn't notice they came from pendulum, not the datetime library itself, but when I wrote the failing test, datetime.date also failed for the same reason - TIL! But since stream_slices are Iterable[Optional[Mapping[str, Any]]], there could be datetimes or other custom objects in that Any.

[erohmensing]

And thanks, will format and add changelog info etc. so that I can release it :)

Edit: just remembered changelog and versioning are handled by the action, so convenient 💯