You need to pull the node object out of the variables array.

$node = $variables['node'];

In certain preprocess functions this may not be available, so you can try the request service:

$node = \Drupal::request()->get('node');

The object must be of type Node. Therefore:

$node->getType() == 'events'

You need to pull the node object out of the variables array.

$node = $variables['node'];

In certain preprocess functions this may not be available, so you can try the request service:

$node = \Drupal::request()->get('node');

The object must be of type Node. Therefore:

$node->getType() == 'events'

As Berdir mentioned, you should check and ensure that $node is a valid Node object to see if it is an instance of NodeInterface before operating on it. This will prevent fatal errors in the event that $variables['node'] is actually a node and not some ad-hoc variable created in code from which you can't call methods on:

Example 1 (using $variables array):

if (isset($variables['node']) && $variables['node'] instanceof NodeInterface) {
  $node = $variables['node'];
  $title = $node->getTitle();
  $type = $node->getType();
  // more code...
}

Example 2 (using the request):

$node = \Drupal::request()->get('node');

if (isset($node) && $node instanceof NodeInterface) {
  $title = $node->getTitle();
  $type = $node->getType();
  // more code...
}

The object must be of type Node. Therefore:

$node->getType() == 'events'

You need to pull the node object out of the variables array.

$node = $variables['node'];

In certain preprocess functions this may not be available, so you can try the request service:

$node = \Drupal::request()->get('node');

The object must be of type Node. Therefore:

$node->getType() == 'events'