Wrong corpus access error message when opening a command

The current ‘500 error’ message is not informative.

Commands using a CQL query as an argument, produce a message “La requête CQL est mal formulée : \nFailed to get properties” which is misleading, and may cause the user to indefinitely search for a CQL expression that works (and that cannot be found).

Solution

• If the corpus is not accessible the command must not open its interface
• change the error message to explicitly tell : the corpus is not available and the admin must be contacted

(from redmine: issue id 2903, created on 2020/10/06 by Matthieu Decorde)