template location was ignored if html was defined

also if html was empty

Viewer/src/configuration/mappers.ts

@@ -52,6 +52,10 @@ class HTMLMapper implements IMapper {
                         val = true;
                     } else if (val === "false") {
                         val = false;
+                    } else if (val === "undefeind") {
+                        val = undefined;
+                    } else if (val === "null") {
+                        val = null;
                     } else {
                         var isnum = !isNaN(parseFloat(val)) && isFinite(val);///^\d+$/.test(val);
                         if (isnum) {

Viewer/src/templating/templateManager.ts

@@ -530,7 +530,7 @@ export class Template {
     private _getTemplateAsHtml(templateConfig: ITemplateConfiguration): Promise<string> {
         if (!templateConfig) {
             return Promise.reject('No templateConfig provided');
-        } else if (templateConfig.html !== undefined) {
+        } else if (templateConfig.html) {
             return Promise.resolve(templateConfig.html);
         } else {
             let location = this._getTemplateLocation(templateConfig);