last table row delete throwing error (#4270)

Co-authored-by: Gerard Rovira <gerardrovira@meta.com>

packages/lexical-table/src/LexicalTableUtils.ts

@@ -461,11 +461,8 @@ export function $deleteTableRow__EXPERIMENTAL(): void {
   }
   const columnCount = gridMap[0].length;
   const nextRow = gridMap[focusEndRow + 1];
-  const nextRowNode = grid.getChildAtIndex(focusEndRow + 1);
-  invariant(
-    DEPRECATED_$isGridRowNode(nextRowNode),
-    'Expected GridNode childAtIndex(%s) to be RowNode',
-    String(focusEndRow + 1),
+  const nextRowNode: null | DEPRECATED_GridRowNode = grid.getChildAtIndex(
+    focusEndRow + 1,
   );
   for (let row = focusEndRow; row >= anchorStartRow; row--) {
     for (let column = columnCount - 1; column >= 0; column--) {
@@ -488,6 +485,7 @@ export function $deleteTableRow__EXPERIMENTAL(): void {
         cellStartRow + cell.__rowSpan - 1 > focusEndRow
       ) {
         cell.setRowSpan(cell.__rowSpan - (focusEndRow - cellStartRow + 1));
+        invariant(nextRowNode !== null, 'Expected nextRowNode not to be null');
         if (column === 0) {
           $insertFirst(nextRowNode, cell);
         } else {