Errors arrive with what caused them

Some errors say almost nothing on their own. In Node, TypeError: fetch failed is the usual example: the reason the request failed sits in the error's cause.

The Node and Python SDKs (0.1.1 and later) now send the whole chain of underlying errors as causes. Your agent sees ENOTFOUND or a refused connection right next to the error.

Grouping is unchanged, so existing errors stay where they are. Update the SDK to start sending causes.