Improve error handling

[matthiasdv]

connect-node micro error responses look like this:

[#126] Received on "_INBOX.FvYLakh0ymAubAlyJ8p1cQ.p6AF4ctJ"
Nats-Service-Error: an error occurred: connector name can only contain letters, numbers, and underscores
Nats-Service-Error-Code: 500

connector name can only contain letters, numbers, and underscores

Where:

• Nats-Service-Error is a friendly user-facing error description.
• Nats-Service-Error-Code is an HTTP status that control-plane can use
• body contains the full error, which is useful while developing against connect

Errors returned by the Connect SDK provide access to this:

// try to get a connector
conn, err := c.GetConnector(name, timeout)
if err != nil {

// use helper
friendlyMsg := client.ErrorMessage(err)

// or
var svcErr *client.ConnectServiceError
if errors.As(err, &svcErr) {
    // Full internal error (for logging)
    fullErr := svcErr.Error()

    // Friendly message for users "an error occurred: connector name can only contain letters, numbers, and underscores"
    friendly := svcErr.Body()

    // Error code "500"
    code := svcErr.Code
}