add NatSpec for some non obvious errors

Author: Whytecrowe

contracts/price/IZNSCurvePricer.sol

@@ -7,9 +7,17 @@ import { IZNSPricer } from "../types/IZNSPricer.sol";
 
 interface IZNSCurvePricer is ICurvePriceConfig, IZNSPricer {
 
+    /**
+     * @notice Reverted when multiplier passed by the domain owner
+     * is equal to 0 or more than 10^18, which is too large.
+     */
     error InvalidMultiplierPassed(uint256 multiplier);
 
-    // TODO upd: "ZNSCurvePricer: incorrect value set causes the price spike at maxLength."
+    /**
+     * @notice Reverted when `priceConfig` set by the owner does not result in a proper asymptotic curve
+     * and one of it's incorrect values causes the price spike at maxLength, meaning that the price
+     * for a domain label shorter than `baseLength` (the one before `minPrice`) becomes higher than `minPrice`.
+     */
     error InvalidConfigCausingPriceSpikes(
         bytes32 configsDomainHash,
         uint256 minPrice,

contracts/registrar/IZNSSubRegistrar.sol

@@ -10,8 +10,15 @@ import { IZNSPricer } from "../types/IZNSPricer.sol";
  * @title IZNSSubRegistrar.sol - Interface for the ZNSSubRegistrar contract responsible for registering subdomains.
 */
 interface IZNSSubRegistrar is IDistributionConfig {
+    /**
+     * @notice Reverted when someone other than parent owner is trying to buy a subdomain under the parent that is locked\
+     * or when the parent provided does not exist.
+     */
     error ParentLockedOrDoesntExist(bytes32 parentHash);
 
+    /**
+     * @notice Reverted when the buyer of subdomain is not approved by the parent in it's mintlist.
+     */
     error SenderNotApprovedForPurchase(bytes32 parentHash, address sender);
 
     /**

contracts/types/IZNSPricer.sol

@@ -7,9 +7,15 @@ pragma solidity 0.8.26;
  * @notice Base interface required to be inherited by all Pricing contracts to work with zNS
  */
 interface IZNSPricer {
-    // TODO upd: add natspec for all new errors !
+    /**
+     * @notice Reverted when someone is trying to buy a subdomain under a parent that is not set up for distribution.
+     * Specifically it's prices for subdomains.
+     */
     error ParentPriceConfigNotSet(bytes32 parentHash);
 
+    /**
+     * @notice Reverted when domain owner is trying to set it's stake fee percentage higher than 100% (uint256 "10,000").
+     */
     error FeePercentageValueTooLarge(uint256 feePercentage, uint256 maximum);
 
     /**

contracts/upgrade-test-mocks/distribution/ZNSSubRegistrarMock.sol

@@ -15,7 +15,7 @@ import { StringUtils } from "../../utils/StringUtils.sol";
 import { PaymentConfig } from "../../treasury/IZNSTreasury.sol";
 import { NotAuthorizedForDomain, ZeroAddressPassed, DomainAlreadyExists } from "../../utils/CommonErrors.sol";
 
-// TODO upd: convert all these errors as well !!
+
 enum AccessType {
     LOCKED,
     OPEN,

contracts/utils/StringUtils.sol

@@ -51,16 +51,11 @@ library StringUtils {
         if (length == 0 || length >= MAX_INT)
             revert DomainLabelTooLongOrNonexistent(s);
 
-        for (uint256 i; i < length;) {
+        for (uint256 i; i < length; ++i) {
             bytes1 b = nameBytes[i];
             // Valid strings are lower case a-z, 0-9, or a hyphen
             if (!((b > 0x60 && b < 0x7B) || (b > 0x2F && b < 0x3A) || b == 0x2D))
                 revert DomainLabelContainsInvalidCharacters(s);
-
-            // TODO upd: remove all unchecked blocks everywhere !
-            unchecked {
-                ++i;
-            }
         }
     }
-}
+}