svelte-fullcalendar VS ics-merger

I'm trying to install the svelte-fullcalendar package in my app, but when I run it, I get the following cryptic error:

I made a few things for my personal use that are used often that I'm quite pleased with, in no particular order:

1. Wallpaper adhesive (https://github.com/jacobmischka/wallpaper-adhesive), an electron app I made ages ago when electron was still relatively new that creates spanned wallpapers for multimonitor setups based on your displays' resolutions. I use it every time I change my wallpapers, every month or so.

2. ics-merger (https://github.com/jacobmischka/ics-merger), a suite of tools including a webapp to merge separate calendar feeds together into a grouped feed, with possible subgroups. One can navigate through the subgroups, see event details, and subscribe to a merged feed, among other similar things. I made it for work, where it's used as the master departmental calendar feed.

3. Tea whistle (https://github.com/jacobmischka/tea-whistle), my second simple microcontroller project I made for my mother for her birthday because her teapot doesn't have a whistle so she kept accidentally boiling it over. It just polls the attached thermometer and beeps when the temperature is over boiling. She uses it every day and says she hasn't boiled it over once since!

4. inmytime.zone (https://github.com/jacobmischka/inmytime.zone), a simple webapp that allows you to create a URL that converts the time you give it into the local timezone of whoever is viewing it. It's effectively just a clone of https://everytimezone.com/ or one of the many other similar tools, but much less busy and without ads. I let the domain expire a few months ago, so it's not currently available, but I just renewed it so it should be again once the domain servers propagate.

5. Gym notebook (https://github.com/jacobmischka/gym_notebook), a flutter app I made when flutter was still quite new to track my workouts using firebase for storage. It's quite rough around the edges, fetches data from the network way more often than necessary, and needs a few bugfixes and could use a bit of work, but it's still good enough for me to use it 4-5 times per week.