contracts-bedrock: less compiler warnings (#2970)

* contracts-bedrock: less compiler warnings

Cleans up compiler warnings that were introduced in https://github.com/ethereum-optimism/optimism/pull/2938.
A bunch of unused variables are deleted, reverts are being asserted on
so no need to assign variables.

* contracts-bedrock: regenerate snapshot
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

packages/contracts-bedrock/.gas-snapshot

@@ -194,23 +194,23 @@ RLPReader_Test:test_readBytes_invalidStringLength() (gas: 3768)
 RLPReader_Test:test_readBytes_revertListItem() (gas: 3922)
 RLPReader_Test:test_readList_dictTest1() (gas: 23791)
 RLPReader_Test:test_readList_empty() (gas: 4472)
-RLPReader_Test:test_readList_incorrectLengthInArray() (gas: 4213)
-RLPReader_Test:test_readList_int32Overflow() (gas: 3958)
-RLPReader_Test:test_readList_int32Overflow2() (gas: 4024)
-RLPReader_Test:test_readList_invalidShortList() (gas: 3858)
-RLPReader_Test:test_readList_invalidValue() (gas: 3790)
-RLPReader_Test:test_readList_leadingZerosInLongLengthArray1() (gas: 4196)
-RLPReader_Test:test_readList_leadingZerosInLongLengthArray2() (gas: 4180)
-RLPReader_Test:test_readList_leadingZerosInLongLengthList1() (gas: 38563)
+RLPReader_Test:test_readList_incorrectLengthInArray() (gas: 4210)
+RLPReader_Test:test_readList_int32Overflow() (gas: 3955)
+RLPReader_Test:test_readList_int32Overflow2() (gas: 4021)
+RLPReader_Test:test_readList_invalidShortList() (gas: 3855)
+RLPReader_Test:test_readList_invalidValue() (gas: 3787)
+RLPReader_Test:test_readList_leadingZerosInLongLengthArray1() (gas: 4193)
+RLPReader_Test:test_readList_leadingZerosInLongLengthArray2() (gas: 4177)
+RLPReader_Test:test_readList_leadingZerosInLongLengthList1() (gas: 38560)
 RLPReader_Test:test_readList_listOfLists() (gas: 9619)
 RLPReader_Test:test_readList_listOfLists2() (gas: 12479)
 RLPReader_Test:test_readList_longList1() (gas: 29013)
 RLPReader_Test:test_readList_longList2() (gas: 202895)
-RLPReader_Test:test_readList_longStringLength() (gas: 3856)
+RLPReader_Test:test_readList_longStringLength() (gas: 3853)
 RLPReader_Test:test_readList_multiList() (gas: 12025)
-RLPReader_Test:test_readList_nonOptimalLongLengthArray1() (gas: 4203)
-RLPReader_Test:test_readList_nonOptimalLongLengthArray2() (gas: 4226)
-RLPReader_Test:test_readList_notLongEnough() (gas: 3844)
+RLPReader_Test:test_readList_nonOptimalLongLengthArray1() (gas: 4200)
+RLPReader_Test:test_readList_nonOptimalLongLengthArray2() (gas: 4223)
+RLPReader_Test:test_readList_notLongEnough() (gas: 3841)
 RLPReader_Test:test_readList_shortListMax1() (gas: 40662)
 RLPReader_Test:test_readList_stringList() (gas: 16796)
 RLPReader_Test:test_readString_emptyString() (gas: 1719)

packages/contracts-bedrock/contracts/test/RLPReader.t.sol

@@ -274,61 +274,61 @@ contract RLPReader_Test is CommonTest {
 
     function test_readList_invalidShortList() external {
         vm.expectRevert("Invalid RLP short list.");
-        RLPReader.RLPItem[] memory list = RLPReader.readList(hex"efdebd");
+        RLPReader.readList(hex"efdebd");
     }
 
     function test_readList_longStringLength() external {
         vm.expectRevert("Invalid RLP short list.");
-        RLPReader.RLPItem[] memory list = RLPReader.readList(hex"efb83600");
+        RLPReader.readList(hex"efb83600");
     }
 
     function test_readList_notLongEnough() external {
         vm.expectRevert("Invalid RLP short list.");
-        RLPReader.RLPItem[] memory list = RLPReader.readList(hex"efdebdaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa");
+        RLPReader.readList(hex"efdebdaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa");
     }
 
     function test_readList_int32Overflow() external {
         vm.expectRevert("Invalid RLP long string.");
-        RLPReader.RLPItem[] memory list = RLPReader.readList(hex"bf0f000000000000021111");
+        RLPReader.readList(hex"bf0f000000000000021111");
     }
 
     function test_readList_int32Overflow2() external {
         vm.expectRevert("Invalid RLP long list.");
-        RLPReader.RLPItem[] memory list = RLPReader.readList(hex"ff0f000000000000021111");
+        RLPReader.readList(hex"ff0f000000000000021111");
     }
 
     function test_readList_incorrectLengthInArray() external {
         vm.expectRevert("Invalid RLP list value.");
-        RLPReader.RLPItem[] memory list = RLPReader.readList(hex"b9002100dc2b275d0f74e8a53e6f4ec61b27f24278820be3f82ea2110e582081b0565df0");
+        RLPReader.readList(hex"b9002100dc2b275d0f74e8a53e6f4ec61b27f24278820be3f82ea2110e582081b0565df0");
     }
 
     function test_readList_leadingZerosInLongLengthArray1() external {
         vm.expectRevert("Invalid RLP list value.");
-        RLPReader.RLPItem[] memory list = RLPReader.readList(hex"b90040000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f");
+        RLPReader.readList(hex"b90040000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f");
     }
 
     function test_readList_leadingZerosInLongLengthArray2() external {
         vm.expectRevert("Invalid RLP list value.");
-        RLPReader.RLPItem[] memory list = RLPReader.readList(hex"b800");
+        RLPReader.readList(hex"b800");
     }
 
     function test_readList_leadingZerosInLongLengthList1() external {
         vm.expectRevert("Provided RLP list exceeds max list length.");
-        RLPReader.RLPItem[] memory list = RLPReader.readList(hex"fb00000040000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f");
+        RLPReader.readList(hex"fb00000040000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f");
     }
 
     function test_readList_nonOptimalLongLengthArray1() external {
         vm.expectRevert("Invalid RLP list value.");
-        RLPReader.RLPItem[] memory list = RLPReader.readList(hex"b81000112233445566778899aabbccddeeff");
+        RLPReader.readList(hex"b81000112233445566778899aabbccddeeff");
     }
 
     function test_readList_nonOptimalLongLengthArray2() external {
         vm.expectRevert("Invalid RLP list value.");
-        RLPReader.RLPItem[] memory list = RLPReader.readList(hex"b801ff");
+        RLPReader.readList(hex"b801ff");
     }
 
     function test_readList_invalidValue() external {
         vm.expectRevert("Invalid RLP short string.");
-        RLPReader.RLPItem[] memory list = RLPReader.readList(hex"91");
+        RLPReader.readList(hex"91");
     }
 }