Crashing when exporting HTML

[AlanDunaway]

I tried exporting HTML two times, and the app crashed just after I name the file and click save/export.

In Replace, I set to replace(transformations menu) ## with <h2>. ## for Calibre is pretty much unusable. Calibre breaks chapters at <h2> tags, not ## markdown tags.

[jdanielp]

I can't reproduce this problem with the following environment:

Manuskript 0.13.1#795e1fa (Python 3.9.7)
* PyQt 5.9.2 (compiled against Qt 5.9.7)
  * Qt 5.9.7 (runtime)
* lxml.etree 4.7.1.0
  * libxml   2.9.12 (compiled: 2.9.12)
  * libxslt  1.1.34 (compiled: 1.1.34)
* pyEnchant N/A (libenchant: N/A)
* pySpellChecker N/A
* Symspellpy 6.7.6
* Markdown 3.3.6

run from source in PyCharm using the book-of-acts sample version 0.13.1 running against my develop branch with a couple of commits after this repo's commit 0182a43b8ec5bf16217da659078843d201388b2b

Is there a repeatable recipe with the book-of-acts sample or can you provide a sample that has the issue?