How to open a file with my cordova app

Question

I am using the webintent cordova plugin to hopefully open a file sent to my app by Dropbox or Inbox.

I added the following in my manifest:

<intent-filter>
    <action android:name="android.intent.action.VIEW" />
    <category android:name="android.intent.category.DEFAULT" />
    <data android:mimeType="*/*" />
    <data android:pathPattern="*.json" />
</intent-filter>

And my app shows up in the list of candidates when using "open with" from Dropbox. So far so good.

But when I run the example code snippet to receive the intent:

window.plugins.webintent.getExtra(window.plugins.webintent.ACTION_VIEW,
  function(extra) {debugger}, function() {debugger}
);

I get an error from cordova.js line 1097. The message is F09 WebIntent1422948397 sError.

What does the error mean and how should I troubleshoot further?

Also, any links to documentation on what happens when I click "open with" from Dropbox or share an attachment from Inbox to another app is welcome.