i dont know what it's wrong with my gengar.
Your geometry is fucked for heatmap skinning. Skin with a different method.
Try checking off the unused influences box
>>513515damm, thk man
Just don't use heatmaps. They're shit. geodesic voxel is far better and it won't make a difference once you export anyway. I would strongly suggest not disabling "remove unused influences". It has nothing to do with this error. Also there's no way that mesh needs 4 max influences.
jesus christ that topology is full of ngons and wide faces that connect to nowhere. even if it did skin, it would deform like shit.