JS Error: Section title on scroll

[virginiacc]

In IE, an error sometimes occurs when scrolling down the page. It does not seem to affect user experience.

Stack trace:

TypeError: Unable to get property 'split' of undefined or null reference
   at b.exports.idToRef (http://www.consumerfinance.gov/static/regulations/js/built/regulations.min.js:5:25017)
   at changeTitle (http://www.consumerfinance.gov/static/regulations/js/built/regulations.min.js:6:11408)
   at n (http://www.consumerfinance.gov/static/regulations/js/built/regulations.min.js:1:21743)
   at b.Events.trigger (http://www.consumerfinance.gov/static/regulations/js/built/regulations.min.js:1:21101)
   at checkActiveSection (http://www.consumerfinance.gov/static/regulations/js/built/regulations.min.js:6:14231)
   at ea.event.dispatch (http://www.consumerfinance.gov/static/regulations/js/built/regulations.min.js:3:24226)
   at Anonymous function (http://www.consumerfinance.gov/static/regulations/js/built/regulations.min.js:5:23549)

To replicate:

• In IE11, navigate to http://www.consumerfinance.gov/eregulations/1026-38/2016-06834
• Scroll down the page. The error will occur as the section title updates based on the current scroll position.
  

[ascott1]

Great catch @virginiacc! Thank you.