Fix panic when annotation of ingress is empty

When the annotation of ingress is not set, the returned value is nil
(not empty map). Trying to assign to this map leads to panic.

Signed-off-by: Jiří Pinkava <j-pi@seznam.cz>

pkg/router/util.go

@@ -29,6 +29,9 @@ func includeLabelsByPrefix(labels map[string]string, includeLabelPrefixes []stri
 }
 
 func filterMetadata(meta map[string]string) map[string]string {
+	if meta == nil {
+		meta = map[string]string{}
+	}
 	// prevent Flux from overriding Flagger managed objects
 	meta[toolkitReconcileKey] = toolkitReconcileValue
 	meta[helmDriftDetectionKey] = toolkitReconcileValue