Fix "cannot mix BigInt and other types" error

[ephys]

Hello,

I'm trying to update this library in sequelize (sequelize/sequelize#14187), but the newer version crashes with TypeError: Cannot mix BigInt and other types, use explicit conversions.

The error is thrown by this line:

return negate ? -1 * result : result;

According to the code, result is always a BigInt, so -1 * result will always throw. I've changed -1 to -1n in the code and it resolved the issue.

[rusher]

merge to develop branch, this will be part of 3.0.1 release

[ephys]

Thank you!