If I click either on “Resitance & Immunities” or “Conditions & Active Effects” after opening a character sheet, quite often I’ve got the following error message in the pop-up, which is replaced by the actual info after ~5s
Thanks for reporting! What browser is this happening in? 
IIRC, it was in Chromium, under Linux (I was playing around w/4 Different browsers yesterday)
I’m not able to reproduce every timethough