plaintext decode out of range about seal-python HOT 4 CLOSED

from seal import *
from seal_helper import *

print_example_banner("Example: BFV Basics")

parms = EncryptionParameters(scheme_type.BFV)
poly_modulus_degree = 4096  # you can use yours, it just fast
parms.set_poly_modulus_degree(poly_modulus_degree)
parms.set_coeff_modulus(CoeffModulus.BFVDefault(poly_modulus_degree))
parms.set_plain_modulus(1024)  #  any positive integer, maybe a prime number and keep it small will be better in theory

context = SEALContext.Create(parms)
print_parameters(context)
evaluator = Evaluator(context)
encoder = IntegerEncoder(context)
keygen = KeyGenerator(context)
public_key = keygen.public_key()
secret_key = keygen.secret_key()
encryptor = Encryptor(context, public_key)
decryptor = Decryptor(context, secret_key)

value1 = -7
plain1 = Plaintext(encoder.encode(value1))
value2 = 25
plain2 = Plaintext(encoder.encode(value2))


x1 = Ciphertext()
encryptor.encrypt(plain1, x1)
evaluator.add_plain_inplace(x1, plain2)
evaluator.multiply_plain_inplace(x1, plain2)

p1 = decryptor.decrypt(x1)
v1 = encoder.decode_int64(p1)
print(v1)  # 450