[WIP] [TwigBundle] [Exception] Make return value similar to error.json.twig
feature #11078 [WIP] [TwigBundle] [Exception] Make return value similar to error.json.twig (clemens-tolboom)

This PR was squashed before being merged into the 2.6-dev branch (closes #11078).

Discussion
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[WIP] [TwigBundle] [Exception] Make return value similar to error.json.twig

| Q             | A
| ------------- | ---
| Bug fix?      | I guess this is a bug
| New feature?  | The exception structure changes for the default
| BC breaks?    | The exception structure changes for the default
| Deprecations? | [yes|no]
| Tests pass?   | [yes|no]
| Fixed tickets |
| License       | MIT
| Doc PR        |

The result for `error.json.twig` and `exception.json.twig` differ making the client forced to check for it's result.

We think the structure should be the same to make the ie a javascript client try to respond similar for --env=dev|prod

Commits
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4a59f98 [WIP] [TwigBundle] [Exception] Make return value similar to error.json.twig