[HttpFoundation] Silent only JSON errors
Catch exceptions to restore the error handler
Fix JsonSerializable namespace
Clear json_last_error
Merge branch '2.5'

* 2.5:
  typo fixed in AbstractProcessTest (getoutput() => getOutput())
  Avoid question mark and asterisk in folder names to prevent windows filesystem issues.
  [Translation] [Config] Clear libxml errors after parsing XML file
  check for the Validator if forms are enabled
  Clear json_last_error
  Fix JsonSerializable namespace
  Catch exceptions to restore the error handler
  [HttpFoundation] Silent only JSON errors