Switching from glitch-soc to vanilla makes MastoFE unusable

I updated Pleroma to commit 42d2c8d9 and tried MastoFE to see what was new in the update. I clicked on "Switch to Vanilla Flavour" to see what's the difference between glitch-soc and vanilla Mastodon, and the window is just blank. When I open the console in Firefox and Chromium (latest stable versions), it throws this error in Chromium
and in Firefox

Since the window is blank, I can't really switch back to glitch-soc. I tried flushing cookies and localstorage, it didn't work.