Add more comments and asserts

[StanislavBreadless]

What ❔

Why ❔

Checklist

• PR title corresponds to the body of PR (we generate changelog entries from PRs).
• Tests for the changes have been added / updated.
• Documentation comments have been added / updated.

[github-actions]

Coverage after merging sb/more-comments into draft-v31 will be

90.82%

Coverage Report

File	Stmts	Branches	Funcs	Lines	Uncovered Lines
contracts/bridge
BridgeHelper.sol	100%	100%	100%	100%
BridgedStandardERC20.sol	96.25%	100%	92.31%	97.01%	231–232
L1ERC20Bridge.sol	97.78%	100%	100%	97.30%	267
L1Nullifier.sol	96.12%	100%	100%	95.40%	446–447, 450, 476, 729, 732, 734, 750
UpgradeableBeaconDeployer.sol	100%	100%	100%	100%
contracts/bridge/asset-router
AssetRouterBase.sol	98.53%	100%	100%	98.21%	132
L1AssetRouter.sol	91.62%	100%	86.67%	92.70%	116, 331, 342, 424–425, 444, 602, 613, 627, 632
contracts/bridge/asset-tracker
AssetTrackerBase.sol	93.33%	100%	88.89%	95.24%	88
GWAssetTracker.sol	92.11%	100%	92.50%	92.05%	135–137, 158, 208–210, 212–214, 219–220, 348–350, 356, 369, 504, 694
L1AssetTracker.sol	91.75%	100%	100%	90.61%	113, 131–132, 145, 150, 162, 326, 328–329, 332, 566, 573, 579, 585, 591, 619, 84
LegacySharedBridgeAddresses.sol	83.33%	100%	100%	81.82%	39, 41
contracts/bridge/interfaces
AssetHandlerModifiers.sol	75%	100%	100%	66.67%	13
contracts/bridge/ntv
L1NativeTokenVault.sol	98.17%	100%	100%	97.70%	191, 193
NativeTokenVaultBase.sol	98.94%	100%	100%	98.73%	164, 170
contracts/common
MessageVerification.sol	88.24%	100%	87.50%	88.46%	34, 41–42
ReentrancyGuard.sol	100%	100%	100%	100%
contracts/common/l2-helpers
L2ContractHelper.sol	98.11%	100%	100%	97.78%	102
SystemContractsCaller.sol	52.50%	100%	60%	51.43%	42–43, 45, 47, 49, 51, 64, 67, 70, 73, 76, 81, 87, 89, 91, 94, 96
contracts/common/libraries
DataEncoding.sol	95.90%	100%	95.83%	95.92%	193, 283, 301, 307
DynamicIncrementalMerkle.sol	100%	100%	100%	100%
DynamicIncrementalMerkleMemory.sol	98.96%	100%	100%	98.84%	196
FullMerkle.sol	98.28%	100%	100%	98.11%	109
FullMerkleMemory.sol	93.81%	100%	100%	93.33%	114, 131, 149, 163, 194, 90
Merkle.sol	100%	100%	100%	100%
MessageHashing.sol	98.67%	100%	100%	98.46%	154
SemVer.sol	100%	100%	100%	100%
UncheckedMath.sol	100%	100%	100%	100%
UnsafeBytes.sol	100%	100%	100%	100%
ZKSyncOSBytecodeInfo.sol	100%	100%	100%	100%
contracts/common/libraries/TransientPrimitives
TransientPrimitives.sol	100%	100%	100%	100%
contracts/core/bridgehub
BridgehubBase.sol	96.86%	100%	100%	96.23%	155, 304, 320, 580, 584, 587
L1Bridgehub.sol	91.92%	100%	100%	90.91%	137, 218, 293, 297–298, 301, 311, 96
L2Bridgehub.sol	66.67%	100%	60%	68.57%	102–103, 111, 113–114, 123, 128–129, 131–132, 75
contracts/core/chain-asset-handler
ChainAssetHandlerBase.sol	85.86%	100%	92.31%	84.88%	114, 121–122, 140–142, 191, 194, 203–204, 340, 344, 366
L1ChainAssetHandler.sol	88.07%	100%	82.35%	89.13%	182, 271, 273–275, 314, 87–88, 92–93
L2ChainAssetHandler.sol	84.21%	100%	80%	85.71%	120, 124, 69, 93
contracts/core/chain-registration
ChainRegistrationSender.sol	89.13%	100%	100%	86.84%	104, 127, 47, 94, 98
contracts/core/ctm-deployment
CTMDeploymentTracker.sol	100%	100%	100%	100%
contracts/core/message-root
L1MessageRoot.sol	95.24%	100%	91.67%	96.08%	170–171
L2MessageRoot.sol	62.22%	100%	45.45%	67.65%	109, 116, 120–121, 42–43, 52–53, 57, 64, 80
MessageRootBase.sol	92.78%	100%	100%	91.36%	110, 130, 134, 211, 282, 301, 345
contracts/governance
AccessControlRestriction.sol	100%	100%	100%	100%
ChainAdmin.sol	97.87%	100%	100%	97.30%	44
ChainAdminOwnable.sol	100%	100%	100%	100%
Governance.sol	100%	100%	100%	100%
L2ProxyAdminDeployer.sol	100%	100%	100%	100%
PermanentRestriction.sol	100%	100%	100%	100%
ServerNotifier.sol	100%	100%	100%	100%
TransitionaryOwner.sol	100%	100%	100%	100%
contracts/governance/restriction
Restriction.sol	100%	100%	100%	100%
RestrictionValidator.sol	100%	100%	100%	100%
contracts/interop
AttributesDecoder.sol	100%	100%	100%	100%
InteropCenter.sol	95.56%	100%	88.46%	96.48%	120–121, 132, 176–177, 575, 659
InteropDataEncoding.sol	100%	100%	100%	100%
InteropHandler.sol	96.58%	100%	100%	96.15%	346, 368, 373, 64
L2InteropRootStorage.sol	0%	100%	0%	0%	20–22, 41, 46, 52–53, 58, 60–62, 71, 73–74, 76–77, 81–82, 86, 88
L2MessageVerification.sol	100%	100%	100%	100%
contracts/l2-system/zksync-os
L1MessageGasLib.sol	100%	100%	100%	100%
L1Messenger.sol	94.12%	100%	100%	92.86%	29
SystemContext.sol	100%	100%	100%	100%
ZKOSContractDeployer.sol	0%	100%	0%	0%	15–17, 23, 29, 33–34
contracts/l2-upgrades
L2ComplexUpgrader.sol	0%	100%	0%	0%	23–25, 39, 44, 46, 56, 62–63, 70, 79–81, 84, 86–87
L2GenesisForceDeploymentsHelper.sol	93.71%	100%	100%	93.15%	117, 150, 196, 198, 202, 204–205, 235, 241, 460
L2GenesisUpgrade.sol	0%	100%	0%	0%	30, 37, 39–40, 43, 47–50, 53, 55, 63
L2V30TestnetSystemProxiesUpgrade.sol	0%	100%	0%	0%	101, 107, 30, 35–36, 38, 49, 55, 60, 64, 69, 74, 79, 84, 89, 94
L2V31Upgrade.sol	0%	100%	0%	0%	14–15
SystemContractProxy.sol	88%	100%	66.67%	90.91%	23–24
SystemContractProxyAdmin.sol	60%	100%	66.67%	57.14%	12, 18–19
V31AcrossRecovery.sol	0%	100%	0%	0%	46–48, 67–68, 70–71, 75, 80–81, 96
contracts/state-transition
AccessControlEnumerablePerChainAddressUpgradeable.sol	98.25%	100%	100%	97.83%	179
ChainTypeManagerBase.sol	96.19%	100%	100%	95.29%	206, 209, 383, 473, 478, 620, 683, 721, 797
EraChainTypeManager.sol	94.12%	100%	100%	92.86%	39
ZKsyncOSChainTypeManager.sol	80%	100%	66.67%	83.33%	26–27
contracts/state-transition/chain-deps
DiamondInit.sol	94.23%	100%	100%	94%	72, 76, 80
DiamondProxy.sol	100%	100%	100%	100%
StoredBatchHashing.sol	100%	100%	100%	100%
contracts/state-transition/chain-deps/facets
Admin.sol	91.71%	100%	93.75%	91.35%	110–112, 197, 201, 205, 275, 300–301, 385, 424, 94–96, 98–99
Committer.sol	90.80%	100%	100%	90%	205, 230, 237, 283,