Indentation in front of HTML block crashes WYSIWYG editor

[jadham2]

Describe the bug

CommonMark specification and GFM specification specifies that start conditions for HTML blocks can be indented by up to three spaces. after >= 4 spaces, it becomes a code block (correct behavior). The current regex for reHTMLTag only looks at tags immediately starting on a line. This causes it to crash when displaying in WYSIWYG mode since it can not match the tag.

To Reproduce

Steps to reproduce the behavior:

1. Enter Markdown mode
2. Type any HTML tag with 1-3 spaces in front of it
3. Attempt to switch to WYSIWYG mode

Expected behavior

The tag should be matched and treated as a normal HTML tag.

Desktop (please complete the following information):

Browser: Firefox v121.0

Additional context

"@toast-ui/react-editor": "^3.2.3"