Trouble installing coc-inline-jest

[CallumHoward]

I get this when I enable the extension using :CocList -> extensions -> coc-inline-jest 0.1.2

[coc.nvim]Error on active extension coc-inline-jest: TypeError: Cannot read property 'split' of undefined
    at Runner.createProcess [as _createProcess] (webpack-internal:///4:36:38)
    at Runner.start (webpack-internal:///7:122:32)
    at JestProcess.startRunner (webpack-internal:///993:50:21)
    at new JestProcess (webpack-internal:///993:13:14)
    at JestProcessManager.runJest (webpack-internal:///995:30:29)
    at JestProcessManager.run (webpack-internal:///995:40:21)
    at JestProcessManager.startJestProcess (webpack-internal:///995:22:25)
    at VimJest.startProcess (webpack-internal:///985:16:52)
    at Object.exports.createTestLensProvider (webpack-internal:///2:20:13)
    at <anonymous>

And get the following if I do inlineJest.toggle

[coc.nvim]Command: inlineJest.toggle not found

Jest: 23.6.0
Jest package location: <project-root>/node_modules/jest
Neovim: stable 0.4.3
macOS: 10.15.3