fix: strict container check

Author: vvo

lib/utils.js

@@ -1,10 +1,15 @@
-var isString = require('lodash/lang/isString');
-
-function getContainerNode(value) {
-  if (isString(value)) {
-    return document.querySelector(value);
+function getContainerNode(selectorOrHTMLElement) {
+  if (typeof selectorOrHTMLElement === 'string') {
+    return document.querySelector(selectorOrHTMLElement);
+  } else if (!isDomElement(selectorOrHTMLElement)) {
+    throw new Error('Container must be `string` or `HTMLElement`');
   }
-  return value;
+
+  return selectorOrHTMLElement;
+}
+
+function isDomElement(o) {
+  return o instanceof HTMLElement || o && o.nodeType > 0;
 }
 
 function renderTemplate(template, data) {