fix(datatable): is sortable console error (carbon-design-system#11568)

Author: sangeethababu9223

packages/carbon-web-components/src/components/data-table/table.ts

@@ -820,7 +820,7 @@ class CDSTable extends HostListenerMixin(LitElement) {
     });
     const columns = [...this._tableHeaderRow.children];
     let sortDirection;
-    let columnIndex = -1;
+    let columnIndex = 0;
     columns.forEach((column, index) => {
       if (
         column.hasAttribute('sort-direction') &&