Error when pasting HTML containing /data-slate-fragment="(.+?)"/ in text

[12joan]

Description
The regular expression catchSlateFragment matches /data-slate-fragment="(.+?)"/ anywhere in pasted HTML, including in text nodes. This casues an error if the capture group isn't a properly formatted Slate fragment. The error doesn't crash the editor, but it does prevent pasting.

Recording
https://user-images.githubusercontent.com/4272090/222422917-00f36461-3fe2-47a0-8dc7-77ee2594652e.mp4

Sandbox
https://www.slatejs.org/examples/richtext

Steps
To reproduce the behavior:

1. Open Rich Text example in Browser A and Browser B
2. In Browser A, type data-slate-fragment="[any text here]"
3. Copy all text
4. Paste into Browser B
5. Paste fails, error in console

In the case of Safari, pasting into the same editor also causes the error, since we cannot rely on application/x-slate-fragment (see #4998).

Expectation
We should ensure that data-slate-fragment is only parsed in the attributes of a HTML tag, not in text nodes. If fully parsing the HTML isn't an option, the following regular expression should suffice, so long as < tags are properly encoded in text nodes (which they should be).

/<[^>]+data-slate-fragment="(.+?)"/

Environment

• Slate Version: 0.91.7
• Operating System: macOS
• Browser: Safari, (Chrome and Firefox when pasting between browsers)