feature #10491 [Admin] Form validation error  (Tomanhez)
feature #10491 [Admin] Form validation error  (Tomanhez)

This PR was merged into the 1.6-dev branch.

Discussion
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| Q               | A
| --------------- | -----
| Branch?         | master
| Bug fix?        | no
| New feature?    | yes
| BC breaks?      | no
| Deprecations?   | no
| License         | MIT


**Random form screenshots:**

![Screenshot 2019-07-03 at 14 51 19](https://user-images.githubusercontent.com/39232096/60593310-c2349700-9da2-11e9-837f-2f692fc0bc69.png)

![Screenshot 2019-07-03 at 14 51 46](https://user-images.githubusercontent.com/39232096/60593321-c791e180-9da2-11e9-95ae-845ef87543fb.png)

![Screenshot 2019-07-03 at 14 58 07](https://user-images.githubusercontent.com/39232096/60593450-117ac780-9da3-11e9-9d69-91e9aa967edb.png)




Commits
-------

910dbd15ffc5ef77a060387cf4ecc68e2b5a3446 Add tests
2ee3142325ef11d8150108403c9a78257f66cbd5 Add form_error_checker

Sylius/SyliusUiBundle,Sylius/SyliusUiBundle