Merge: lib/popcorn: replace json_error method by something more useful

Signed-off-by: Alexandre Terrasa <alexandre@moz-code.org>

Pull-Request: #2438

diff --cc lib/popcorn/pop_validation.nit
index 181c47a,86860e5..9c54b76
--- 1/lib/popcorn/pop_validation.nit
--- 2/lib/popcorn/pop_validation.nit
+++ b/lib/popcorn/pop_validation.nit
@@@ -95,10 -95,8 +95,8 @@@ en
  #
  # Errors messages are grouped into *scopes*. A scope is a string that specify wich
  # field or document the error message is related to.
- #
- # See `HttpResponse::json_error`.
  class ValidationResult
 -      super Jsonable
 +      super Serializable
  
        # Object parsed during validation
        #