fix: update error message for more than 1 instance.

pkg/controller/prometheus.go

@@ -112,7 +112,7 @@ func (c *Controller) getPrometheus(ctx context.Context) (promv1.PrometheusInterf
 		return nil, errors.New("no Prometheus or PrometheusAgent found in namespace " + ns)
 	}
 	if len(instances) > 1 {
-		return nil, errors.New("more than one Prometheus or PrometheusAgent instance found with name " + promName)
+		return nil, errors.New("more than one Prometheus or PrometheusAgent instance found in namespace " + ns + ".")
 	}
 
 	return instances[0], nil