refactor: remove errors from lib

src/FixedRateIrm.sol

@@ -4,7 +4,6 @@ pragma solidity 0.8.19;
 import {IIrm} from "../lib/morpho-blue/src/interfaces/IIrm.sol";
 import {IFixedRateIrm} from "./interfaces/IFixedRateIrm.sol";
 
-import {ErrorsLib} from "./libraries/ErrorsLib.sol";
 import {MarketParamsLib} from "../lib/morpho-blue/src/libraries/MarketParamsLib.sol";
 import {Id, MarketParams, Market} from "../lib/morpho-blue/src/interfaces/IMorpho.sol";
 
@@ -19,6 +18,13 @@ contract FixedRateIrm is IFixedRateIrm {
     /// @notice Emitted when a borrow rate is set.
     event SetBorrowRate(Id indexed id, uint256 newBorrowRate);
 
+    /* ERRORS */
+
+    /// @dev Thrown when the rate is already set for this market.
+    string public constant RATE_ALREADY_SET = "rate already set";
+    /// @dev Thrown when trying to set the rate at zero.
+    string public constant RATE_ZERO = "rate zero";
+
     /* STORAGE */
 
     /// @notice Borrow rates.
@@ -28,8 +34,8 @@ contract FixedRateIrm is IFixedRateIrm {
 
     /// @inheritdoc IFixedRateIrm
     function setBorrowRate(Id id, uint256 newBorrowRate) external {
-        require(_borrowRate[id] == 0, ErrorsLib.RATE_ALREADY_SET);
-        require(newBorrowRate != 0, ErrorsLib.RATE_ZERO);
+        require(_borrowRate[id] == 0, RATE_ALREADY_SET);
+        require(newBorrowRate != 0, RATE_ZERO);
 
         _borrowRate[id] = newBorrowRate;
 

src/libraries/ErrorsLib.sol

@@ -11,10 +11,4 @@ library ErrorsLib {
 
     /// @dev Thrown when the caller is not Morpho.
     string internal constant NOT_MORPHO = "not Morpho";
-
-    /// @dev Thrown when the rate is already set for this market.
-    string internal constant RATE_ALREADY_SET = "rate already set";
-
-    /// @dev Thrown when trying to set the rate at zero.
-    string internal constant RATE_ZERO = "rate zero";
 }

test/forge/FixedRateIrmTest.sol

@@ -35,12 +35,12 @@ contract FixedRateIrmTest is Test {
         vm.assume(newBorrowRate1 != 0);
         vm.assume(newBorrowRate2 != 0);
         fixedRateIrm.setBorrowRate(id, newBorrowRate1);
-        vm.expectRevert(bytes(ErrorsLib.RATE_ALREADY_SET));
+        vm.expectRevert("rate already set");
         fixedRateIrm.setBorrowRate(id, newBorrowRate2);
     }
 
     function testSetBorrowRateRateZero(Id id) external {
-        vm.expectRevert(bytes(ErrorsLib.RATE_ZERO));
+        vm.expectRevert("rate zero");
         fixedRateIrm.setBorrowRate(id, 0);
     }