Is Javascript injection supposed to work even for web pages with no Javascript whatsoever?

One of the methods in my applications is using the Javascript injection trick described in this thread to capture the entire HTML of a web page after rendering:

// This call inject JavaScript into the page which just finished rendering.
browser.loadUrl(
  "javascript:window.HTMLOUT.processHTML(
    document.getElementsByTagName('html')[0].innerHTML);");

It works -- even for very rich web pages -- but when it tries to handle in the same manner pages that do not have any Javascript in them, it generates the following error:

ERROR/Web Console(1335): Uncaught TypeError: 
  Cannot call method 'processHTML' of undefined at :1

In my search for possible root cause or explanation, I found quite a few postings describing an Uncaught TypeError: Cannot call method *** of undefined at :1 with two typical answers:

1. Use webView.getSettings().setDomStorageEnabled(true);
2. "Usually, when the error is of the form Cannot call method 'X' of undefined, it means that whatever object you are attempting to call X from does not exist."

Well, the cause of the problem in my case cannot be #1 (setDomStorageEnabled), because I already have that set correctly in my code!

So the only other possible explanation is that the object from which I am trying to call processHTML() does not exits. That object is named HTMLOUT and it is created in the activity's onCreate(), after creating a WebView object and initializing it with setWebViewClient():

webView.addJavascriptInterface(new JavascriptInterface(this, webView), "HTMLOUT");

That leads me to suspect that the JavascriptInterface object instantiation fails for some reason.

This is where my understanding stops and my questions begin:

1. Does what I have been describing so far make sense?
2. If so, why would the 开发者_开发知识库JavascriptInterface object instantiation fail?
3. Is it possible that the reason for the failure is the non-existence of any Javascript in the original HTML?
4. What can be done to work around this problem?