[SDK] FIx merkle tree proof for Drop contracts (#4344)

internal discussion: https://thirdwebdev.slack.com/archives/C04DP04AF1V/p1725028836481129

<!-- start pr-codex -->

---

## PR-Codex overview
**Focus:** This PR focuses on fixing the Merkle tree proof for Drop contracts in the `thirdweb` package.

### Detailed summary
- Fixed sorting of leaves in `MerkleTree.ts`.
- Renamed `ADDRESS_ZERO` to `ZERO_ADDRESS`.
- Updated logic for fetching proofs in `fetchProofsForClaimer`.
- Added a test for large Merkle trees in `MerkleTree.test.ts`.

> ✨ Ask PR-Codex anything about this PR by commenting with `/codex {your question}`

<!-- end pr-codex -->

Author: kien-ngo

.changeset/hip-apples-beg.md

@@ -0,0 +1,5 @@
+---
+"thirdweb": patch
+---
+
+Fix merkletree proof for Drop contracts

packages/thirdweb/src/merkletree/MerkleTree.test.ts

@@ -1,4 +1,5 @@
 import { describe, expect, it } from "vitest";
+import type { Hex } from "../utils/encoding/hex.js";
 import { stringToBytes } from "../utils/encoding/to-bytes.js";
 import { MerkleTree } from "./MerkleTree.js";
 
@@ -14,6 +15,35 @@ describe("MerkleTree", () => {
         `"0xebd2ffa91ce49e68a5ae1283e5babdf2655f8ea9ea0ee36ed525cc41d171a882"`,
       );
     });
+
+    it("should return root for large merkle trees", () => {
+      const leaves: Hex[] = [
+        "0xe1b12834247548c6bf6a9d37d2090a5f41beda62be633f705bc7c6e924342b4d",
+        "0x232570d6677f4e4b8947d8369750a4da492511d19e104db19dfae1200c3ff4db",
+        "0xe30d909533984527552083c16f23927cb9928c2e01b7252989f1c4fb9714deca",
+        "0xd13d5d1bf095147532482f25aac6d72905850864aab58f9dac28beb655dc4726",
+        "0xa0eea66d581045e22cbeccd59027e62b5d753fd3118f068b444bceec601be03f",
+        "0x222cd80957bf16ed8ce63a492a5035830cc2bfe04e2d46cc28e3aacb5db1277a",
+        "0xb1525c3a1a9d0fa632857acd0216609a80c19293fc3273f4cac664ca49a9e323",
+        "0x18b19c2a11bd54e98cc841bc8863d3e8582da3dd21903aedfe6745d41083653b",
+        "0xc198129437401b73388fa41dfaa82457015716050c6632364a1db94db1f0fb19",
+        "0x7621bd1c73bb5d8487459d8be36c5445a65a7fda457972d7f9de22a826739281",
+        "0x1cc9ca923d763f8de998921de43da79d6415eaff9b875e3e619c246fc26160b7",
+        "0xb4526c4f954e3230701cb7a392081007c050e950d886a25bac5fb14e3639e258",
+        "0x7d00f9a67344ed46afab13a398ea4bbf40915283f08f5caaf7d128a836361943",
+        "0xb11d4116f885aa50e9e9cbddf61b4d582413cd959302c68bfc0430fe8d5f609b",
+        "0xd474bee9ba879f0e0ae0827601642460e5439b4c3acb69da07b77ae2779a4eb2",
+        "0xb2b902dfab66d5dbee090467f02abd14c49e11f92a7d58fda53982f006f4360c",
+        "0x7ed8ec6456a2418c91d362f5ef5b4865d68a1df05722fe0fa9ecf23e0fc7e935",
+        "0xb1efbe628e4a0062c6f241f2ccd3663269fafb4305d2cbe33c6f94d0aea8e195",
+      ];
+      const merkleTree = new MerkleTree(leaves);
+      const hexProof = merkleTree.getHexRoot();
+
+      expect(hexProof).toBe(
+        "0x58053466a63f980211c457688c927035d61a7717b7744afe3758138ce66a6fda",
+      );
+    });
   });
 
   describe("getHexProof", () => {

packages/thirdweb/src/merkletree/MerkleTree.ts

@@ -26,7 +26,7 @@ export class MerkleTree {
       el instanceof Uint8Array ? el : hexToBytes(el),
     );
 
-    this.leaves = this.leaves.sort();
+    this.leaves = this.leaves.sort(compareUint8Arrays);
 
     this.createHashes(this.leaves);
   }

packages/thirdweb/src/utils/extensions/drops/fetch-proofs-for-claimers.ts

@@ -1,5 +1,5 @@
 import {
-  ADDRESS_ZERO,
+  ZERO_ADDRESS,
   isNativeTokenAddress,
 } from "../../../constants/addresses.js";
 import type { ThirdwebContract } from "../../../contract/contract.js";
@@ -69,8 +69,8 @@ export async function fetchProofsForClaimer(options: {
       });
     }),
   );
-  const tree = new MerkleTree(hashedEntries);
   // 5. get the proof for the claimer + the sub merkle tree root
+  const tree = new MerkleTree(hashedEntries);
   const entry = shardData.entries.find(
     (i) => i.address.toLowerCase() === claimer.toLowerCase(),
   );
@@ -88,11 +88,11 @@ export async function fetchProofsForClaimer(options: {
     )
     .concat(shardData.proofs);
   // 6. return the proof and the entry data for the contract call
-  const currencyAddress = (entry.currencyAddress || ADDRESS_ZERO) as Address;
+  const currencyAddress = (entry.currencyAddress || ZERO_ADDRESS) as Address;
   const currencyDecimals = await (async () => {
     if (
       isNativeTokenAddress(currencyAddress) ||
-      currencyAddress === ADDRESS_ZERO
+      currencyAddress === ZERO_ADDRESS
     ) {
       return 18;
     }