Drupal\Core\Routing\RouteCompiler::compile($route) assumes that the '$route' object is injected.

Problem:
\Drupal\Core\Routing\RouteCompiler::compile($route) generates a \Drupal\Core\Routing\CompiledRoute object but without injecting the '$route' in it. This causes "Notice: Undefined property: Drupal\Core\Routing\CompiledRoute::$route" when the methodes getOptions, getDefaults and getRequirements are called.

The issue can be easily reproduced with enabled 'Devel' module on page devel/php:

$route = new \Symfony\Component\Routing\Route('/');
\Drupal\Core\Routing\RouteCompiler::compile($route)->getDefaults();

Steps to reproduce in Drupal 9

For Drupal 9, devel module has removed the devel/php page so you have to use the devel_php module.

• Install devel and devel_php modules
• Login as admin
• Optional: Enable All messages, with backtrace information -- /admin/config/development/logging
• Go to /devel/php
• Paste this code:
  

  $route = new \Symfony\Component\Routing\Route('/');
  \Drupal\Core\Routing\RouteCompiler::compile($route)->getDefaults();
  

• Note the error on the page
• Go to /admin/reports/dblog
• Note the error in the logs