HTML Guide for hyphens
Malformed comment syntax has been found, check out the affected comment.
HTML comments are helpful to leave notes about the code right next to it. To create a comment, it must start with <!-- and end with -->, as in this example:
<!-- Good comment -->
<!--
Comments can
be multi-line
-->
A common cause for a malformed comment is using too many hyphens (-) as in this example:
<!-- Wrong comment -->