Use of leader() causes pdf generation to fail in 53

[bubonicfred]

I'm using weasyprint via pandoc to generate printout files of essay collections from markdown. When generating the table of contents with the leader() attribute the pdf fails to generate and I get a traceback which ends in

File "/home/usr/.local/lib/python3.8/site-packages/weasyprint/layout/inlines.py", line 80, in handle_leaders text_box, = leader_box.children ValueError: not enough values to unpack (expected 1, got 0) Error producing PDF.

The relevant CSS I'm using is nav ul li a::after { content: leader('.') target-counter(attr(href), page); float: right; }
I am by far not the best at CSS, and the documentation for this function is patchy, So I could easily be at fault. 52 Simply skipped over leader(), and removing it allows the pdf to generate

[liZe]

Hello!

Thanks a lot for this bug report.

Using float for a block containing leaders is a bit "dangerous", because floats somehow try to be as small as they can be. So, in many cases, the current implementation doesn’t display the leaders at all, because they’re not "mandatory". The specification is not really clear about this, and I think that nobody knows how it’s supposed to work exactly.

Removing "float: right" should do what you expect.

But of course, it shouldn’t crash, we need a fix for this problem.