I used fennel/Love2D for my last game jam, there is a modification required to make the absolute minimum template work with love.js. You need to remove the extra thread listening on the terminal for input for the web / standalone binaries to work.
If you want to steal my export setup, here is the git repo to my entry this year, which has some niceties such as not needing to compile the fennel to Lua to make it run in love.js.
Also, probably a bigger project than this jam allows, but consider emacs with fennel-mode for editing. It’s a first class experience and has everything baked in, even a REPL.