I have been using drupal examples https://www.drupal.org/project/examples and developing my own examples for practice. But I have come against an issue I can't workout. Below is my link to the block code I have been developing.
I can get the block to display under admin/structure/block, but when I press the "Display Block" button in the overlay I get no response can someone tell me why? See image
The error I am getting from the ajax call is
ajax.js?v=8.1.8:965 Uncaught AjaxError: An AJAX HTTP error occurred. HTTP Result Code: 200 Debugging information follows. Path: /d8/admin/structure/block/add/pnc_block_test/pnc?region=-1 StatusText: OK ResponseText: Fatal error: Class 'Drupal\Core\block\BlockBase' not found in /vagrant/src/d8/modules/custom/pnc/pnc_block_test/src/Plugin/Block/PncBlockTest.php on line 23
What I have trying to achieve is the following