Return friendlyNames as answer to get_group_membership (#4210)

* Return friendlyNames as answer to get_group_membership

It would be a lot more useful, if you'd return the friendly names of the groups 😉

* Make the linter happy

* Gracefully echo warning if response is undefined

* Making friendship with the linter

Sorry, really shoud have used an IDE

lib/extension/legacy/deviceGroupMembership.js

@@ -29,7 +29,18 @@ class DeviceGroupMembership extends Extension {
             `genGroups`, 'getMembership', {groupcount: 0, grouplist: []}, {}, true,
         );
 
-        const {grouplist, capacity} = response;
+        if (!response) {
+            logger.warn(`Couldn't get group membership of ${entity.device.ieeeAddr}`);
+            return;
+        }
+
+        let {grouplist, capacity} = response;
+
+        grouplist = grouplist.map((gid) => {
+            const g = settings.getGroup(gid);
+            return g ? g.friendlyName : gid;
+        });
+
         const msgGroupList = `${entity.device.ieeeAddr} is in groups [${grouplist}]`;
         let msgCapacity;
         if (capacity === 254) {