Issue with running CodeAsTree mold on process buffer

[ikappaki]

Hi,

I've tried to follow the steps in capture links from html with playground but noticed the html to tree source step failing with the following error:

Wrong type argument: arrayp, nil.

Steps to reproduce:

1. Follow instructions from the article to retrieve the html from the nyxt articles page (I've introduced the additional (tree-sitter-mode) line):

   (progn
   (switch-to-buffer (url-retrieve-synchronously "https://nyxt.atlas.engineer/articles"))
   (goto-char (point-min))
   (delete-region (point-min) url-http-end-of-headers)
   (html-mode)
   (tree-sitter-mode))

2. M-x me-mold RET and select CodeAsTree give the above error.

The issue appears to be related with the mold trying to use the non-existant buffer file name from the async process.

Patch to follow.