stroep.core.StringUtil.js

// Note the addition of if(matches) on line 8 below

replaceVars: function(value, props)
  {
		if (!value || !props) return value;
		
		var matches = value.match(/{.*?}/ig);
		if(matches) {
			for(var i = 0, leni = matches.length; i < leni; i++)
			{
				var match = matches[i];
				var matchValues = match.split(/{|}/ig).join("");
				
				value = value.split(match).join(stroep.core.StringUtil.findPropValue(match, matchValues, props));
			};
		}
		return value;
	},
	
//...

In reference to http://blog.stroep.nl/2012/07/javascript-template-system/.

You need to add a check to see if there are actually any {tag} patterns otherwise the template crashes when no tags are included.