bug symfony#14859 Improve the config validation in TwigBundle (stof)

This PR was merged into the 2.3 branch.

Discussion
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Improve the config validation in TwigBundle

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | symfony#14858
| License       | MIT
| Doc PR        | n/a

This ensures we have better error messages in case of misconfiguration instead of having crappy errors from Twig (which does not validates its options fully either, missing these things)

Commits
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f4dfee3 Improve the config validation in TwigBundle

Author: fabpot

src/Symfony/Bundle/TwigBundle/DependencyInjection/Configuration.php

@@ -129,13 +129,13 @@ private function addTwigOptions(ArrayNodeDefinition $rootNode)
                 ->end()
                 ->scalarNode('autoescape_service')->defaultNull()->end()
                 ->scalarNode('autoescape_service_method')->defaultNull()->end()
-                ->scalarNode('base_template_class')->example('Twig_Template')->end()
+                ->scalarNode('base_template_class')->example('Twig_Template')->cannotBeEmpty()->end()
                 ->scalarNode('cache')->defaultValue('%kernel.cache_dir%/twig')->end()
                 ->scalarNode('charset')->defaultValue('%kernel.charset%')->end()
-                ->scalarNode('debug')->defaultValue('%kernel.debug%')->end()
-                ->scalarNode('strict_variables')->end()
+                ->booleanNode('debug')->defaultValue('%kernel.debug%')->end()
+                ->booleanNode('strict_variables')->end()
                 ->scalarNode('auto_reload')->end()
-                ->scalarNode('optimizations')->end()
+                ->integerNode('optimizations')->min(-1)->end()
                 ->arrayNode('paths')
                     ->normalizeKeys(false)
                     ->useAttributeAsKey('paths')