toInt method
Safe only if the magnitude fits in a double-safe int — delegates to
Uint128.toInt()'s own guard, so it throws IntegerError otherwise
(use toBigInt for the general case).
Implementation
int toInt() {
final negative = isNegative;
final magnitudeBits = negative ? ((~_bits) + Uint128.one) : _bits;
final mag = magnitudeBits.toInt();
return negative ? -mag : mag;
}