Defensively JSON.pase+JSON.stringify inputs into removeCircular to prevent NPEs

[joehan]

Description

Some complex objects that overwrote toJSON were breaking the structured logger. Specifically, calling removeCircular on some complex objects (for example, #907 ) could cause JSON.stringify to throw null pointer errors when called on those objects. This fix should ensure that any object can be safely logged.

Testing

I tested out the case in #907, and I was able to successfully log moment() without errors:
{"structuredData":"2021-06-28T22:31:17.125Z","severity":"INFO","message":"Hello logs!"}

[joehan]

Seems like this broke some unit tests too, taking a look now.

[joehan]

Welp, this approach won't work... For simple circular objects, JSON.stringify throws an error, so we need to do something a bit more nuanced to handle both simple circular objects and objects that implement toJSON