Merge branch 'master' into nalipiev/schematics-10.2

Author: Lipata

projects/igniteui-angular/src/lib/grids/tree-grid/tree-grid-add-row-ui.spec.ts

@@ -110,5 +110,22 @@ describe('IgxTreeGrid - Add Row UI #tGrid', () => {
             // should have same parent record.
             expect(addedRow.treeRow.parent).toBe(row.treeRow.parent);
         });
+
+        it('should allow adding row to empty grid', () => {
+            treeGrid.data = [];
+            fix.detectChanges();
+
+            expect(treeGrid.rowList.length).toBe(0);
+
+            // begin add row for empty grid
+            treeGrid.beginAddRowByIndex(null, -1);
+            fix.detectChanges();
+            endTransition();
+
+            treeGrid.endEdit(true);
+            fix.detectChanges();
+
+            expect(treeGrid.rowList.length).toBe(1);
+        });
     });
 });

projects/igniteui-angular/src/lib/grids/tree-grid/tree-grid.component.ts

@@ -526,9 +526,9 @@ export class IgxTreeGridComponent extends IgxGridBaseDirective implements GridTy
     protected _getParentRecordId() {
         if (this.addRowParent.asChild) {
             return super._getParentRecordId();
-        } else {
+        } else if (this.addRowParent.rowID !== null && this.addRowParent.rowID !== undefined) {
             const spawnedForRecord =  this._gridAPI.get_rec_by_id(this.addRowParent.rowID);
-            return spawnedForRecord.parent?.rowID;
+            return spawnedForRecord?.parent?.rowID;
         }
     }