However, copying and pasting that source into the Script text box causes a segfault on Fossil 2.19.

i'll look into this later today, thank you for the report. By "script text box" you presumably mean in the skin editor?

Which OS/platform are you on?

FWIW, my tip for including JS/CSS into a skin is to instead check the JS/CSS files into the tree and add links to them in the skin header. There's a documented example over at:

http://fossil.wanderinghorse.net/r/cwal/dir/doc/highlightjs

That greatly simplifies skin maintenance and such files can be linked to from within embedded docs as well, as in this example:

http://fossil.wanderinghorse.net/r/cwal/file?name=whcl/manual/api-index.md&ci=a52a55226a0db78d&txt=1

No worries.

I tested this some more and it looks like adding any JS at all causes a segfault, even a single character.

I'm on Linux/amd64

The minified JS really isn't all that big.

It also crashes with an empty field. That's now fixed in the trunk. Thank you for reporting it.

Thank you!