fix: revert with ContractNotRegistered on zero-address registry lookup

src/generated/FlareFtsoWords.pointers.sol

@@ -10,7 +10,7 @@ pragma solidity ^0.8.25;
 // file needs the contract to exist so that it can be compiled.
 
 /// @dev Hash of the known bytecode.
-bytes32 constant BYTECODE_HASH = bytes32(0x69ffc4160d6551b77f501f51e6e53d7825dcd7318519779f877261ebd37b7da0);
+bytes32 constant BYTECODE_HASH = bytes32(0x068dba29da80c86736f8a1ea3cc5bae76f15405f03046cda8e9b99fe0a654acf);
 
 /// @dev The hash of the meta that describes the contract.
 bytes32 constant DESCRIBED_BY_META_HASH = bytes32(0x4ccb316fd35a2abbee0016f38926a4c95b6270b229c85a9acf8a3a52b36bfedc);

src/lib/registry/LibFlareContractRegistry.sol

@@ -30,23 +30,38 @@ string constant FTSO_V2_LTS_NAME = "FtsoV2";
 /// contract registry.
 string constant FEE_CALCULATOR_NAME = "FeeCalculator";
 
+/// @notice Thrown when a name lookup in the Flare contract registry returns
+/// address(0). IFlareContractRegistry documents address(0) as the not-found
+/// sentinel; propagating a zero-typed contract handle silently would cause
+/// every subsequent call to revert with a confusing low-level error.
+/// @param name The registry name that resolved to address(0).
+error ContractNotRegistered(string name);
+
 library LibFlareContractRegistry {
     /// Sugar for getting the FTSO registry address from the Flare contract
-    /// registry.
+    /// registry. Reverts with ContractNotRegistered if the name is not found.
     function getFtsoRegistry() internal view returns (IFtsoRegistry) {
-        return IFtsoRegistry(FLARE_CONTRACT_REGISTRY.getContractAddressByName(FTSO_REGISTRY_NAME));
+        address addr = FLARE_CONTRACT_REGISTRY.getContractAddressByName(FTSO_REGISTRY_NAME);
+        if (addr == address(0)) revert ContractNotRegistered(FTSO_REGISTRY_NAME);
+        return IFtsoRegistry(addr);
     }
 
     /// Sugar for getting the FTSO V2 LTS contract address from the Flare
-    /// contract registry.
+    /// contract registry. Reverts with ContractNotRegistered if the name is not
+    /// found.
     //forge-lint: disable-next-line(mixed-case-function)
     function getFtsoV2LTS() internal view returns (FtsoV2Interface) {
-        return FtsoV2Interface(FLARE_CONTRACT_REGISTRY.getContractAddressByName(FTSO_V2_LTS_NAME));
+        address addr = FLARE_CONTRACT_REGISTRY.getContractAddressByName(FTSO_V2_LTS_NAME);
+        if (addr == address(0)) revert ContractNotRegistered(FTSO_V2_LTS_NAME);
+        return FtsoV2Interface(addr);
     }
 
     /// Sugar for getting the FeeCalculator contract address from the Flare
-    /// contract registry.
+    /// contract registry. Reverts with ContractNotRegistered if the name is not
+    /// found.
     function getFeeCalculator() internal view returns (IFeeCalculator) {
-        return IFeeCalculator(FLARE_CONTRACT_REGISTRY.getContractAddressByName(FEE_CALCULATOR_NAME));
+        address addr = FLARE_CONTRACT_REGISTRY.getContractAddressByName(FEE_CALCULATOR_NAME);
+        if (addr == address(0)) revert ContractNotRegistered(FEE_CALCULATOR_NAME);
+        return IFeeCalculator(addr);
     }
 }

test/src/lib/registry/LibFlareContractRegistry.t.sol

@@ -7,16 +7,21 @@ import {LibFork} from "test/fork/LibFork.sol";
 import {
     LibFlareContractRegistry,
     IFtsoRegistry,
+    FLARE_CONTRACT_REGISTRY,
     FTSO_REGISTRY_NAME,
     FTSO_V2_LTS_NAME,
-    FEE_CALCULATOR_NAME
+    FEE_CALCULATOR_NAME,
+    ContractNotRegistered
 } from "src/lib/registry/LibFlareContractRegistry.sol";
+import {LibFlareContractRegistryExternal} from "test/src/lib/registry/LibFlareContractRegistryExternal.sol";
 import {FtsoV2Interface} from "src/vendor/flare-smart-contracts-v2/userInterfaces/LTS/FtsoV2Interface.sol";
 import {IFeeCalculator} from "src/vendor/flare-smart-contracts-v2/userInterfaces/IFeeCalculator.sol";
 
 uint256 constant BLOCK_NUMBER = 31843105;
 
 contract LibFlareContractRegistryTest is Test {
+    LibFlareContractRegistryExternal internal external_ = new LibFlareContractRegistryExternal();
+
     constructor() {
         vm.createSelectFork(LibFork.rpcUrlFlare(vm), BLOCK_NUMBER);
     }
@@ -26,6 +31,44 @@ contract LibFlareContractRegistryTest is Test {
         assertEq(address(ftsoRegistry), address(0x13DC2b5053857AE17a4f95aFF55530b267F3E040));
     }
 
+    /// When the Flare contract registry resolves the FtsoRegistry name to
+    /// address(0) (the documented not-found sentinel), getFtsoRegistry MUST
+    /// revert with the specific ContractNotRegistered error rather than
+    /// returning a zero-typed handle. Removing the guard in the library makes
+    /// this test fail (the getter would return address(0) instead of
+    /// reverting).
+    function testGetFtsoRegistryZeroAddressReverts() external {
+        vm.mockCall(
+            address(FLARE_CONTRACT_REGISTRY),
+            abi.encodeWithSelector(FLARE_CONTRACT_REGISTRY.getContractAddressByName.selector, FTSO_REGISTRY_NAME),
+            abi.encode(address(0))
+        );
+        vm.expectRevert(abi.encodeWithSelector(ContractNotRegistered.selector, FTSO_REGISTRY_NAME));
+        external_.getFtsoRegistry();
+    }
+
+    /// As above, for the FtsoV2 LTS getter.
+    function testGetFtsoV2LTSZeroAddressReverts() external {
+        vm.mockCall(
+            address(FLARE_CONTRACT_REGISTRY),
+            abi.encodeWithSelector(FLARE_CONTRACT_REGISTRY.getContractAddressByName.selector, FTSO_V2_LTS_NAME),
+            abi.encode(address(0))
+        );
+        vm.expectRevert(abi.encodeWithSelector(ContractNotRegistered.selector, FTSO_V2_LTS_NAME));
+        external_.getFtsoV2LTS();
+    }
+
+    /// As above, for the FeeCalculator getter.
+    function testGetFeeCalculatorZeroAddressReverts() external {
+        vm.mockCall(
+            address(FLARE_CONTRACT_REGISTRY),
+            abi.encodeWithSelector(FLARE_CONTRACT_REGISTRY.getContractAddressByName.selector, FEE_CALCULATOR_NAME),
+            abi.encode(address(0))
+        );
+        vm.expectRevert(abi.encodeWithSelector(ContractNotRegistered.selector, FEE_CALCULATOR_NAME));
+        external_.getFeeCalculator();
+    }
+
     function testGetFtsoV2LTS() external view {
         FtsoV2Interface ftsoV2 = LibFlareContractRegistry.getFtsoV2LTS();
         assertEq(address(ftsoV2), address(0xB18d3A5e5A85C65cE47f977D7F486B79F99D3d32));

test/src/lib/registry/LibFlareContractRegistryExternal.sol

@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: LicenseRef-DCL-1.0
+// SPDX-FileCopyrightText: Copyright (c) 2020 Rain Open Source Software Ltd
+pragma solidity =0.8.25;
+
+import {LibFlareContractRegistry, IFtsoRegistry} from "src/lib/registry/LibFlareContractRegistry.sol";
+
+/// External wrapper around the internal library getters so that calling them via
+/// `this.<fn>()` produces a dedicated external call frame. `vm.expectRevert`
+/// asserts the *next call frame* reverts; an inlined internal library call has
+/// no frame of its own, so the wrapper is required to observe the revert.
+contract LibFlareContractRegistryExternal {
+    function getFtsoRegistry() external view returns (address) {
+        return address(LibFlareContractRegistry.getFtsoRegistry());
+    }
+
+    function getFtsoV2LTS() external view returns (address) {
+        return address(LibFlareContractRegistry.getFtsoV2LTS());
+    }
+
+    function getFeeCalculator() external view returns (address) {
+        return address(LibFlareContractRegistry.getFeeCalculator());
+    }
+}