Hey samber. Thanks for this library – it has been very useful.

This is an attempt to fix this issue.

In the current implementation, a call such as

type Foo struct {
  Bar string
  Amp string
}
slog.Info("Log message", "foo", Foo{Bar: "bar", Amp: "amp"})

will send JSON like

{..., "foo": "{Bar:bar Amp:amp}"}

where the Foo value has been stringified prior to JSON serialization. Similarly, integers and floats will appear as strings in the JSON sent to datadog.

This PR passes through types which have a reasonable JSON representation without converting them to strings first. The slog.Info call above now sends JSON like

{..., "foo": {"Bar": "bar", "Amp": "amp"}}

I've attempted to add tests which illustrate the fix and which break if the 'bug fix' commit is reverted. The test for the Handler is not ideal as it tests a private function, but I think it's a reasonable alternative to adding some quite complex mocking.