Copy object to prevent exception in react native

[HazAT]

This fixes:
getsentry/sentry-react-native#57
getsentry/sentry-react-native#64

[mitsuhiko]

What if we do something else here and just check for Object.isFrozen(crumb) and continue? In theory since a frozen crumb means it already passed the react native bridge we should not need to do any changes to it.

[LewisJEllis]

Object.isFrozen is IE9+, but we support IE8. Object.assign is ES2015, use our objectMerge helper instead.

[LewisJEllis]

Use objectMerge

[mitsuhiko]

I would check for the existence of isFrozen and skip if we have that function and the object is frozen. That entire branch only matters for react native.

[LewisJEllis]

Yea, sure, I don't have any opinion on what the right thing to be doing is here w.r.t. react-native etc, just want to make sure we keep compatibility in good shape.

[benvinegar]

@HazAT – Can we add some kind of cursory test? Then I'd be glad to approve.

[benvinegar]

@HazAT – would you mind adding a comment about why we do this for react native, and why it's okay if Object.isFrozen isn't called in environments where it isn't supported (maybe link to this PR?). Last thing and then I'll merge.

[HazAT]

Of course makes sense 👍

isFrozen check was applied