Generating tree structures for HTML with a comment inside a heading or paragraph fails.

[hansjovis]

Generating the tree structure fails for HTML that has a comment within a header or paragraph:

<h1>Hello World!<!-- How are you? --></h1>

The comment gets added to the header as a formatting element, as it should be, but something goes wrong when converting the comment from an Ignored node to a FormattingElement.

It currently errors on the calculation of the start- and end position of the formatting elements.
Specifically on this line, where it fails to get the start tag.

YoastSEO.js/src/tree/builder/cleanup/calculateTextIndices.js

Line 116 in 545ce68

const startTag = element.location.startTag;

More importantly, parse5 recognizes How are you? in the example below as a comment:

<h1>Hello World!</ How are you?