code: func (c *client) CaptureError(ctx context.Context, err error) {
  	// if method called during test which has uninitialized client
  	if c == nil {
  		return
  	}
  	// Extract user information. Ignoring error here but then before using the
  	// object user make sure to check if it wasn't nil.
  	user, _ := extractUserInfo(ctx)
  	reqID := log.ExtractRequestID(ctx)
  
  	c.sendErr <- func() {
  		if user != nil {
  			c.c.SetUserContext(user)
  		}
  
  		additionalContext := make(map[string]string)
  		if reqID != "" {
  			additionalContext["req_ID"] = reqID
  		}
  
  		c.c.CaptureError(err, additionalContext)
  		c.c.ClearContext()
  	}
  }
docs: // CaptureError sends error 'err' to Sentry, meanwhile also sets user
  // information by extracting user information from the context provided