Whenever I swap a Skeletal mesh, the editor crashes

I’m trying to change the mesh of a character, but the editor keeps crashing with this error:

Assertion failed: (Index >= 0) & (Index < ArrayNum) [File:D:\Build++UE4\Sync\Engine\Source\Runtime\Core\Public\Containers/Array.h] [Line: 674]
Array index out of bounds: 73 from an array of size 68

i’ve already changed the mesh in this BP so i really don’t know what the issue might be

could someone help?