Added information when an error occured during validation of an answer of a question
bug #12806 [Console] Removed the use of $this->getHelperSet() as it is null by default (saro0h)

This PR was submitted for the 2.6 branch but it was merged into the 2.5 branch instead (closes #12806).

Discussion
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[Console] Removed the use of $this->getHelperSet() as it is null by default

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #12805
| License       | MIT
| Doc PR        | ~

Before:
![capture d ecran 2014-12-02 a 15 51 38](https://cloud.githubusercontent.com/assets/667519/5264798/303bf87a-7a3e-11e4-9b45-68e8a86bab60.png)

After:
![capture d ecran 2014-12-02 a 16 36 25](https://cloud.githubusercontent.com/assets/667519/5265299/b13190d6-7a41-11e4-9e68-d889ea290cae.png)

Commits
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111b194 Added information when an error occured during validation of an answer of a question