fix: Compatible with empty slots for bodyCell

#4855

Author: tangjinzhou

components/vc-table/Cell/index.tsx

@@ -162,7 +162,15 @@ export default defineComponent<CellProps>({
               index,
               column: column.__originColumn__,
             },
-            () => [childNode === undefined ? value : childNode],
+            () => {
+              const fallback = childNode === undefined ? value : childNode;
+              return [
+                (typeof fallback === 'object' && isValidElement(fallback)) ||
+                typeof fallback !== 'object'
+                  ? fallback
+                  : null,
+              ];
+            },
           );
           childNode = flattenChildren(child as any);
         }