ProcedureRevision#compare_type_de_champ: fix bug comparaison characte…

…r_limit chaine vide vs nil

app/models/procedure_revision.rb

@@ -458,7 +458,7 @@ def compare_type_de_champ(from_type_de_champ, to_type_de_champ, from_coordinates
           to_type_de_champ.filename_for_attachement(:notice_explicative))
       end
     elsif to_type_de_champ.textarea?
-      if from_type_de_champ.character_limit != to_type_de_champ.character_limit
+      if from_type_de_champ.character_limit.presence != to_type_de_champ.character_limit.presence
         changes << ProcedureRevisionChange::UpdateChamp.new(from_type_de_champ,
           :character_limit,
           from_type_de_champ.character_limit,