What if we used underlying amounts instead of hToken amounts in the "redeem" function?

[PaulRBerg]

The redeem function requires users to pass an hToken amount.

This has caused an issue in the past, patched by @surbhiaudichya when she added an if block to handle the case where the division rounding errors resulted in receiving zero underlying in exchange for some non-zero hToken amount:

hifi/packages/protocol/contracts/core/hToken/HToken.sol

Lines 166 to 169 in 3263246

	// Checks: the zero edge case.
	if (underlyingAmount == 0) {
	revert HToken__RedeemUnderlyingZero();
	}

Wouldn't it be better if we asked users to pass an underlying amount instead? That way, there would be no rounding errors. There will remain a bit of dust in the users' accounts, but that's fine, since it's not debt and it doesn't interfere with the liquidator bot.

[PaulRBerg]

Of course, implementing this would have downstream effects in the HifiProxyTarget contract, and hence in the UI as well.

[PaulRBerg]

I'm locking this discussion since this refactor idea has been implemented in d9d7b8e.