panic: runtime error: invalid memory address or nil pointer dereference

I have been trying to use the library but I get the error in the title. Here is the code I am using:

p, q, err := paillier.GenerateSafePrime(
    1024,
    4,
    10000000000,
    rand.Reader,
)
if err != nil {
    panic("DidierCrunchPaillier GenerateSafePrime error: " + err.Error())
}
privateKey := paillier.CreatePrivateKey(p, q)
toEncrypt := big.NewInt(19)
cipher, err := privateKey.Encrypt(toEncrypt, rand.Reader)
if err != nil {
    panic("DidierCrunchPaillier Encrypt error: " + err.Error())
}
plain := privateKey.Decrypt(cipher)
fmt.Println("Plaintext: " + plain.String())

The issue is with the decryption function. Here is the trace:

panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xc0000005 code=0x0 addr=0x0 pc=0x1033a3c]

goroutine 1 [running]:
math/big.(*Int).Mul(0xc00005fde8, 0xc00006c7c0, 0x0, 0x0)
      C:/Program Files/Go/src/math/big/int.go:168 +0x1dc
github.com/didiercrunch/paillier.(*PrivateKey).Decrypt(0xc000104300, 0xc000148028, 0x0)
    C:/Users/eoztu/go/pkg/mod/github.com/didiercrunch/paillier@v0.0.0-20180810105046-753322e473bf/paillier.go:121 +0x1f9
...

When I use small primes as in tests (e.g., 13, 17), enc/dec both works but not with generated primes. Am I using the API wrong?

didiercrunch / paillier

panic: runtime error: invalid memory address or nil pointer dereference #13