Incorrect error handling about starknet-rs

[xJonathanLEI]

Sorry but some of these have already been answered in #446, an issue submitted by yourself. I prefer not to waste my time answering in this case.

[satoshiotomakan]

@xJonathanLEI sorry for the duplicates, my mistake.

[xJonathanLEI]

Unwraps:

starknet-rs/starknet-crypto/src/fe_utils.rs

Line 43 in 91425ad

FieldElement::from_bytes_be(&result).unwrap()

modulus is a FieldElement, and result is mod modulus. So result is always a valid FieldElement.

starknet-rs/starknet-crypto/src/fe_utils.rs

Line 66 in 91425ad

FieldElement::from_bytes_be(&result).unwrap()

result is always smaller than modulus, which is a valid FieldElement itself.

starknet-rs/starknet-curve/src/ec_point.rs

Lines 41 to 56 in 91425ad

	pub fn double_assign(&mut self) {
	if self.infinity {
	return;
	}
	// l = (3x^2+a)/2y with a=1 from stark curve
	let lambda = {
	let dividend = FieldElement::THREE * (self.x * self.x) + FieldElement::ONE;
	let divisor_inv = (FieldElement::TWO * self.y).invert().unwrap();
	dividend * divisor_inv
	};
	let result_x = (lambda * lambda) - self.x - self.x;
	self.y = lambda * (self.x - result_x) - self.y;
	self.x = result_x;
	}

I'm actually not sure about this. This seems to panic when self.y is zero.

starknet-rs/starknet-ff/src/lib.rs

Lines 144 to 170 in 91425ad

	pub fn from_dec_str(value: &str) -> Result<Self, FromStrError> {
	// Ported from:
	// https://github.com/paritytech/parity-common/blob/b37d0b312d39fa47c61c4430b30ca87d90e45a08/uint/src/uint.rs#L599
	let mut res = U256::ZERO;
	for b in value.bytes().map(|b| b.wrapping_sub(b'0')) {
	if b > 9 {
	return Err(FromStrError::InvalidCharacter);
	}
	let r = {
	let product = res.checked_mul(&U256::from_u8(10));
	if product.is_some().into() {
	product.unwrap()
	} else {
	return Err(FromStrError::OutOfRange);
	}
	};
	let r = {
	let sum = r.checked_add(&U256::from_u8(b));
	if sum.is_some().into() {
	sum.unwrap()
	} else {
	return Err(FromStrError::OutOfRange);
	}
	};
	res = r;
	}

We already checked for is_some before unwrapping. It's safe.

Panics:

starknet-rs/starknet-ff/src/lib.rs

Lines 288 to 291 in 91425ad

	} else {
	// TODO: add `checked_floor_div` for panic-less use
	panic!("division by zero");
	}

As mentioned in the comment, panicking on division by zero is the expected behavior, similar to how division by zero panics for any other types.