Thank you for your answer.
I Tried the tool, and made a mess
. Sleeping too little does bad and funny things to our brains.
Among the several terminal manipulations,I overwrote the SidecarCore.bak file, giving me no file to fall back on. I tried several options. Now browsers crash on open and the modified SidecarCore file makes it so every app in focus crashes when using the arrow keys.
It seems the tool broke with the latest Catalina update as per this post:
https://github.com/ben-z/free-sidecar/issues/59#issuecomment-603697315
Better still, the backup I had also overwritten the Catalina backup I had done, and only have one with Mojave and Clover.
Can I use MacOS recovery to re-install the OS? I am using your latest EFI with OpenCore 0.6.1.
If that isn't possible, is there anywhere to download the original and signed SidecarCore file?