bug #12553 [Debug] fix error message on double exception (nicolas-gre…

…kas)

This PR was submitted for the 2.6 branch but it was merged into the 2.3 branch instead (closes #12553).

Discussion
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[Debug] fix error message on double exception

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Commits
-------

1ed7606 [Debug] fix error message on double exception

src/Symfony/Component/Debug/ExceptionHandler.php

@@ -169,7 +169,7 @@ public function getContent(FlattenException $exception)
             } catch (\Exception $e) {
                 // something nasty happened and we cannot throw an exception anymore
                 if ($this->debug) {
-                    $title = sprintf('Exception thrown when handling an exception (%s: %s)', get_class($exception), $exception->getMessage());
+                    $title = sprintf('Exception thrown when handling an exception (%s: %s)', get_class($e), $e->getMessage());
                 } else {
                     $title = 'Whoops, looks like something went wrong.';
                 }