Do not expose message when error is returned

[bridgedragon]

• I have read the Contributing file of the documentation.
• I have searched the issues (including closed ones) and believe that this is not a duplicate.

Issue

If a server error is returned ("Error 500"), the json returned is accompanied by a field "message", that describes the error occurred. This is a security issue, particularly for production environment, because it is exposing server information.

This field should be removed and be used only internally in logs.