bug #17486 [FrameworkBundle] Throw for missing container extensions (kix)

This PR was submitted for the master branch but it was merged into the 2.7 branch instead (closes #17486).

Discussion
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[FrameworkBundle] Throw for missing container extensions

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | none
| License       | MIT
| Doc PR        | none

This covers the case when an existing bundle does not have an extension, and its config is dumped. Before, calling `app/console config:dump` on such bundle lead to FatalErrorException with ```Call to a member function getAlias() on null```, now we process such cases and throw an exception with some explanatory text.

Commits
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884368e Throw for missing container extensions

src/Symfony/Bundle/FrameworkBundle/Command/AbstractConfigCommand.php

@@ -57,6 +57,10 @@ abstract class AbstractConfigCommand extends ContainerDebugCommand
         $bundles = $this->initializeBundles();
         foreach ($bundles as $bundle) {
             if ($name === $bundle->getName()) {
+                if (!$bundle->getContainerExtension()) {
+                    throw new \LogicException(sprintf('Bundle "%s" does not have a container extension.', $name));
+                }
+
                 return $bundle->getContainerExtension();
             }