Improve error message for unknown error in validateTargetRef

vertical-pod-autoscaler/pkg/recommender/input/cluster_feeder.go

@@ -586,7 +586,7 @@ func (feeder *clusterStateFeeder) validateTargetRef(ctx context.Context, vpa *vp
 		return false, condition{conditionType: vpa_types.ConfigUnsupported, delete: false, message: fmt.Sprintf("Error checking if target is a topmost well-known or scalable controller: %s", err)}
 	}
 	if top == nil {
-		return false, condition{conditionType: vpa_types.ConfigUnsupported, delete: false, message: fmt.Sprintf("Unknown error during checking if target is a topmost well-known or scalable controller: %s", err)}
+		return false, condition{conditionType: vpa_types.ConfigUnsupported, delete: false, message: fmt.Sprintf("Unknown error during checking if target %s is a topmost well-known or scalable controller", k)}
 	}
 	if *top != k {
 		return false, condition{conditionType: vpa_types.ConfigUnsupported, delete: false, message: "The targetRef controller has a parent but it should point to a topmost well-known or scalable controller"}

vertical-pod-autoscaler/pkg/target/controller_fetcher/controller_fetcher.go

@@ -76,6 +76,11 @@ type ControllerKeyWithAPIVersion struct {
 	ApiVersion string
 }
 
+// String defines the format for the stringification of ControllerKeyWithAPIVersion
+func (c ControllerKeyWithAPIVersion) String() string {
+	return fmt.Sprintf("ControllerKeyWithAPIVersion %s of %s kind in %s namespace}", c.Name, c.Kind, c.Namespace)
+}
+
 // ControllerFetcher is responsible for finding the topmost well-known or scalable controller
 type ControllerFetcher interface {
 	// FindTopMostWellKnownOrScalable returns topmost well-known or scalable controller. Error is returned if controller cannot be found.