PDF Export Error: "Failed to add header/footer" with Null pdf Type

[HoeYeungHo]

• Searched existing issues to avoid creating duplicates.
• Confirmed that it can be reproduced in built-in themes without customized css.
• Searched http://support.typora.io/

Describe the bug
When exporting a PDF in Typora, the following error is displayed:

Failed to add header / footer.
`pdf` must be of type `string` or `Uint8Array` or `ArrayBuffer`, but was actually of type `null`

As a result, the exported PDF does not include any header or footer content. The settings used for export are shown in the attached screenshot.

To Reproduce

Steps to reproduce the behavior:

1. Set up the page settings as shown in the screenshot (e.g., custom margins, A4 size, and headers/footers with variables like ${pageNo} / ${totalPages}).
2. Export a Markdown file to PDF.
3. Observe the error message and missing header/footer in the exported PDF.

Expected behavior

Headers and footers should be correctly rendered in the exported PDF, without any errors.

Screenshots / Screencasts

Sample Markdown File

Any Markdown file.

Desktop (please complete the following information):

• OS: Windows 11 64-bit
• Typora Version: 1.10.5-dev