Fix bug in service/context audit function

service/context.go

@@ -214,8 +214,9 @@ func (ctx *serviceContext) ValueOrDefault(name string, defaultValue interface{})
 }
 
 func (ctx *serviceContext) AuditChange(eventType string, orgValue, newValue interface{}) {
+	username, _ := ctx.Claim()["username"].(string)
 	event, err := audit.NewEvent(
-		ctx.Claim()["username"].(string), //use username as source (will default to "SYSTEM" if undefined)
+		username, //use username as source (will default to "SYSTEM" if undefined)
 		eventType,
 		orgValue,
 		newValue,