return null if no template could be found

scm-webapp/src/main/java/sonia/scm/template/ServletMustacheFactory.java

@@ -30,6 +30,7 @@
  */
 
 
+
 package sonia.scm.template;
 
 //~--- non-JDK imports --------------------------------------------------------
@@ -129,6 +130,12 @@ public class ServletMustacheFactory extends DefaultMustacheFactory
       logger.warn("could not find resource {}", resourceName);
     }
 
+    if (reader == null)
+    {
+      throw new MustacheTemplateNotFoundException(
+        "could not find template for resource ".concat(resourceName));
+    }
+
     return reader;
   }