Error Messages are not displayed when they are only strings when using nunjucks rendering engine

[tylkomat]

In flash-messages.html the test {% if message %} is always true, either if message is a string or an object, so always the "object" route is taken.

I extended the test to {% if message.title or message.detail or message.list %} which solves this problem, but there should be a better solution.

[tylkomat]

One Option would be to create a custom filter.

In keystone.js add:

var cons = require('consolidate'),
      nunjucks = require('nunjucks');

cons.requires.nunjucks.addFilter('is_object', function(obj) {
    return typeof obj == 'object';
});

and then in templates/mixins/flash-messages.html {% if message %} has to be changed to {% if message | is_object %}.

I can create a pull request if necessary.