readthedocs theme TOC scrolling JS exception

[cgwyllie]

In the readthedocs theme (mkdocs, version 0.16.2) we're seeing an exception from this line: bounds.top = this.offset().top; in the theme.js file.

It seems this was introduced by #1156 and referenced from #803.

We can observe it happening when the currently active TOC item is below the fold (scrolled off screen to the bottom).

Here's the stack trace:

Uncaught TypeError: Cannot read property 'top' of undefined
    at n.fn.init.$.fn.isFullyWithinViewport (theme.js:67)
    at HTMLDocument.<anonymous> (theme.js:74)
    at j (jquery-2.1.1.min.js:2)
    at Object.fireWith [as resolveWith] (jquery-2.1.1.min.js:2)
    at Function.ready (jquery-2.1.1.min.js:2)
    at HTMLDocument.I (jquery-2.1.1.min.js:2)

Testing in Chrome 56.0.2924.87 on macOS 10.12.3.

As a workaround we've created an override theme.js file to remove the scroll behaviour.