Using the watch command crashes NeoVim if I open a project without jest installed?

[NigelGreenway]

When I add the following line to enable watching of jest tests, and I open my NeoVim config, my editor just crashes

jestCommand = require("neotest-jest.jest-util").getJestCommand(vim.fn.expand("%:p:h")) .. " --watch",

When I remove it, I can open nvim anywhere. My understanding here is that this line is needed in order to watch jest tests, without it they shouldn't work. But on investigation, it is currently working... 😕

This is the only adapter I have enabled in my neotest set up so far.