I had the same thing happen with Control Rig. Unreal crashed after attempting to drag a new function into the graph. The Control Rig asset became corrupted, and because it was linked to the Animation Blueprint (which was linked to the Character, which was linked to the Game Mode, which was linked to the Editor Startup Map in the World Settings), the project would immediately crash on open.
I had to temporarily remove the Config folder from the project so it would not load the affected map on launch. However it would still crash if the Character or Animation Blueprints were clicked on. Fortunately I had a backup of the Animation Blueprint on another drive which allowed me to restore that file without the corrupt control rig node in it, and then all other files could open normally again. I had a few other working copies of the Control Rig so I only had to recreate a portion of it.
EDIT: I suppose if one didn’t have a copy of the AnimBP backed up, one could just delete (or rename) the corrupt Control Rig file using your computer’s file browser. Deleting from within Unreal may not have been possible, since it would crash even when right-clicking the file. Deleting the corrupt file may have been an alternative way of allowing the Animation BP to open, since the corrupted file could no longer be found.
However, seeing how unstable Control Rig appears to be (it crashed the Editor again this morning after hitting undo a few times), I’m seriously wondering if it is safe for production use. It also asks to be recompiled every time I open it, which also seems unstable (described here).