Improve the handling of leaveBreadcrumb's metadata property when it cannot be serialized

[hitsvilleusa]

Description

We had breadcrumbs that were not showing up in our error reports, which wasn't discovered until we randomly saw

unable to serialize breadcrumb: not a valid JSON object

in our logs.

The problem was a simple fix ... we were sending a value from an enumerated type, and adding a description, or rawValue, or String(describing: value) all would do the trick. This led to being a bit more robust in our solution and before sending the payload to bugsnag, we converted any non serializable values using String(describing: value).

Describe the solution you'd like
I would like it if we didn't have to pre-process the metadata that we sent to leaveBreadcrumb. Being a little smarter about how to serialize data would be a win, or even if the compiler told us that we needed to fix it on the calling end, would have been a win.

Describe alternatives you've considered
I built out solutions to leverage the compiler and to just convert at runtime when there was an issue, and found that the runtime change was less disruptive overall.

Additional context

[johnkiely1]

Hi @hitsvilleusa,

We're going to take a look into this to see what we can do to improve it. We will keep you updated here. Thanks.

[nickdowell]

• [PLAT-7126] Stop dropping breadcrumbs with invalid metadata #1187

[yousif-bugsnag]

This has now been fixed in v6.12.2 🎉