Steps to reproduce

1. Add the "Access to thesaurus tool" right to a profile with very not much rights.
2. Connect with an user with this thin profile.
3. Try to access to a thesaurus through the ribbon.
4. You get the following error:

   Une erreur inattendue est survenue et elle a empêché l'ouverture de l'outil demandé.
   Error: [Ext.create] Unrecognized class name / alias: Ametys.plugins.thesaurus.tool.ThesaurusTool
   Error: [Ext.create] Unrecognized class name / alias: Ametys.plugins.thesaurus.tool.ThesaurusTool
   at Object.create (http://ametys-recette.onisep.fr/ideo2_recette/plugins/extjs7/resources/ext-all.js:17020:23)
   at constructor.openTool (http://ametys-recette.onisep.fr/ideo2_recette/plugins/core-ui/resources/js/Ametys/tool/factory/BasicToolFactory.js:90:16)
   at constructor.openTool (http://ametys-recette.onisep.fr/ideo2_recette/plugins/core-ui/resources/js/Ametys/tool/ToolsManager.js:329:24)
   at constructor._onItemPress (http://ametys-recette.onisep.fr/ideo2_recette/plugins/thesaurus/resources/js/Ametys/plugins/thesaurus/controller/ThesaurusGalleryController.js:118:30)
   at Object.callback (http://ametys-recette.onisep.fr/ideo2_recette/plugins/extjs7/resources/ext-all.js:9638:30)
   at constructor.fireHandler (http://ametys-recette.onisep.fr/ideo2_recette/plugins/extjs7/resources/ext-all.js:167196:13)
   at constructor.onClick (http://ametys-recette.onisep.fr/ideo2_recette/plugins/extjs7/resources/ext-all.js:167178:13)
   at constructor.fire (http://ametys-recette.onisep.fr/ideo2_recette/plugins/extjs7/resources/ext-all.js:22906:35)
   at constructor.fire (http://ametys-recette.onisep.fr/ideo2_recette/plugins/extjs7/resources/ext-all.js:37964:21)
   at constructor.publish (http://ametys-recette.onisep.fr/ideo2_recette/plugins/extjs7/resources/ext-all.js:37924:25)