Dev here. That sounds like step 8 wasn't completed without errors:

``` sudo codesign -f -s - /System/Library/PrivateFrameworks/SidecarCore.framework/Versions/A/SidecarCore ```

A properly signed SidecarCore modified with free-sidecar shouldn't cause random crashes.

When I have the time I’ll try again, paying special attention to the codesigning output.

I’ll report my results here, unless replies are closed, in which case I’ll comment in the repo.