[Base resolvers] allGroups and allSimpleGroups bugfix

src/graphql/models/groupModel.ts

@@ -105,7 +105,7 @@ export class GroupModel {
      * @rights connectedOrOnplatal
      */
     getAllGroupsByCollection(groups: GroupCollection): Group[] {
-        let res: Group[]
+        let res = new Array<Group>();
 
         for(let s of groups.simpleGroups) {
             res.push(new SimpleGroup(s));
@@ -127,7 +127,7 @@ export class GroupModel {
      * @rights connectedOrOnplatal
      */
     async getAllGroupsBySet(groups: GroupSet): Promise<Group[]> {
-        let res: Group[]
+        let res = new Array<Group>();
 
         for(let g of groups) {
             res.push(await this.getGroup(g));
@@ -145,7 +145,7 @@ export class GroupModel {
      * @rights connectedOrOnplatal
      */
     getAllSimpleGroups(groups: GroupSet): SimpleGroup[] {
-        let res: SimpleGroup[]
+        let res = new Array<SimpleGroup>();
 
         for (let g of groups) {
             res.push(new SimpleGroup(g));