web-ui: Display default message on server errors without message

web-ui/src/app/app.component.ts

@@ -35,6 +35,7 @@ export class AppComponent {
 
       // messages
       'message.serverUnavailable': 'The server unavailable, please try again in a minute',
+      'message.unknownError': 'Unknown error, please try again in a minute',
 
       // actions
       'action.find': 'Find',

web-ui/src/app/services/error.service.ts

@@ -33,8 +33,8 @@ export class ErrorService {
           this.setFieldError(form, fieldName, message);
         }
       } else {
-        const message = element.message;
-        this.notificationService.error(message);
+        this.translateService.get(element.message || 'message.unknownErrors')
+          .subscribe(msg => this.notificationService.error(msg));
       }
     });
   }