Weird behaviour main navigation + console errors

[EnnioWolsink]

When navigating to a page referenced in the main navigation that is on the first level in the hierarchy, the subpages become visible and the minus-sign doesn't seem to work as expected. It does refresh the page and scrolls the viewport to the top. And these errors appear:

[arjangeertsema]

I cannot help you with this issue because I cannot reproduce the error. The problem should be in the content, so my advice is to remove content from the MD file until the problem disappears for root cause analysis.