added empty registerchild function for childregistration process

src/specificClass.js

@@ -76,6 +76,9 @@ class ValveGroupControl {
 
     registerOnChildEvents() {}
 
+    registerChild(child, positionVsParent) {
+    }
+
     isValidSourceForMode(source, mode) {
         const allowedSourcesSet = this.config.mode.allowedSources[mode] || [];
         this.logger.info(`Allowed sources for mode '${mode}': ${allowedSourcesSet}`);