[PT1-115] Fix/self send native

contracts/BaseEscrow.sol

@@ -6,6 +6,8 @@ import { IERC20 } from "openzeppelin-contracts/contracts/token/ERC20/IERC20.sol"
 import { AddressLib, Address } from "solidity-utils/contracts/libraries/AddressLib.sol";
 import { SafeERC20 } from "solidity-utils/contracts/libraries/SafeERC20.sol";
 
+import { SafeSendLib } from "./libraries/SafeSendLib.sol";
+
 import { ImmutablesLib } from "./libraries/ImmutablesLib.sol";
 import { Timelocks, TimelocksLib } from "./libraries/TimelocksLib.sol";
 
@@ -94,7 +96,9 @@ abstract contract BaseEscrow is IBaseEscrow {
      */
     function _ethTransfer(address to, uint256 amount) internal {
         (bool success,) = to.call{ value: amount }("");
-        if (!success) revert NativeTokenSendingFailure();
+        if (!success) {
+            SafeSendLib.safeSend(to, amount);
+        }
     }
 
     /**

contracts/libraries/SafeSendLib.sol

@@ -0,0 +1,14 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+library SafeSendLib {
+    function safeSend(address to, uint256 amount) internal {
+        assembly ("memory-safe") {
+            mstore(0, to)
+            mstore8(11, 0x73) // 0x73 = PUSH20 opcode
+            mstore8(32, 0xff) // 0xff = SELFDESTRUCT opcode
+            pop(create(amount, 11, 22))
+        }
+    }
+}