Fix #1556 Ajax issue when loading bridge playlists
Fix field edition for vocabulary
Merge pull request #750 from nlegoff/fix_1556

[3.8] Fix #1556 Ajax issue when loading bridge playlists
Merge pull request #746 from nlegoff/fix1560

[3.8] Fix #1560 Field edition for vocabulary is broken
Use symfony/debug error handler instead of the deprecated one
Merge pull request #753 from romainneutron/fix-error-handler

[3.8] Use symfony/debug error handler instead of the deprecated one
Fix #1563 : Explicitely declare the default environment to be Application::ENV_PROD