add assert if length of TabController and number of tabs do not match (#29332)

packages/flutter/lib/src/material/tabs.dart

@@ -778,6 +778,17 @@ class _TabBarState extends State<TabBar> {
       }
       return true;
     }());
+
+    assert(() {
+      if (newController.length != widget.tabs.length) {
+        throw FlutterError(
+          'Controller\'s length property (${newController.length}) does not match the \n'
+          'number of tab elements (${widget.tabs.length}) present in TabBar\'s tabs property.'
+        );
+      }
+      return true;
+    }());
+
     if (newController == _controller)
       return;
 
@@ -1122,6 +1133,17 @@ class _TabBarViewState extends State<TabBarView> {
       }
       return true;
     }());
+
+    assert(() {
+      if (newController.length != widget.children.length) {
+        throw FlutterError(
+          'Controller\'s length property (${newController.length}) does not match the \n'
+          'number of elements (${widget.children.length}) present in TabBarView\'s children property.'
+        );
+      }
+      return true;
+    }());
+
     if (newController == _controller)
       return;