Need help : Assertion failed: IsValidIndex(Index)[File:D:\build\++UE5\Sync\Engine\Source\Runtime\Core\Public\Containers\BitArray.h]

I can’t find the answer to my problems, and as always in this case a day passed without any progress…
Anyone knows how to correct this error please?
I’ve tried deleting various project’s folders like Config, Binaries, intermediate, saved, but nothing helped…
That arrived after I migrated a complex animate Cat blueprint and its linked files into my own project from the demo project… but I also added some other files so…

Anyway, I get this everytime I’m trying to open my project :

Assertion failed: IsValidIndex(Index) [File:D:\build++UE5\Sync\Engine\Source\Runtime\Core\Public\Containers\BitArray.h] [Line: 2072]

UnrealEditor_CoreUObject
UnrealEditor_CoreUObject
UnrealEditor_CoreUObject
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
UnrealEditor_Core
kernel32
ntdll

Anyone knows how to deal with this error? Still blocked…