Close stream when there's an error from target

[sfc-gh-elinardi]

Currently when proxy receives an error from a target, it might return a policy evaluation cancelled error instead the actual error from the target.

Policy evaluation cancelled error looks like:

"error":"authz policy evaluation error: eval_cancel_error: caller cancelled query execution"

This is because proxy doesn't immediately close the stream and return the error. It might still be proceeding with executing policy evaluation, which then gets cancelled.
As a result, proxy returns a policy evaluation cancelled error to the client, not the actual error.

Solution

Close stream immediately when receiving error from a target.