Display nice error on invalid schema URL

validata_ui/views.py

@@ -522,7 +522,16 @@ def custom_validator():
         # url of resource to be validated
         url_param = request.args.get("url")
 
-        schema_instance = SchemaInstance.from_parameters(request.args, schema_catalog_map)
+        schema_instance = None
+        try:
+            schema_instance = SchemaInstance.from_parameters(request.args, schema_catalog_map)
+        except json.JSONDecodeError as e:
+            flash_error("Format de schéma non reconnu")
+            return redirect(url_for('home'))
+        except Exception as e:
+            log.exception(e)
+            flash_error("Erreur lors de l'obtention du schéma")
+            return redirect(url_for('home'))
         if schema_instance is None:
             flash_error("Aucun schéma passé en paramètre")
             return redirect(url_for('home'))