fix: Use proper chain ID for signTypedData example (#3013)

When writing the signTypedData example I had based the code on some
example code that hardcoded the chain ID. Instead we should use the
current chain ID, so we can test the Snap on any chain.

Author: FrederikBolding

packages/examples/packages/ethereum-provider/snap.manifest.json

@@ -7,7 +7,7 @@
     "url": "https://github.com/MetaMask/snaps.git"
   },
   "source": {
-    "shasum": "T/7hin+Vhg0SdK8RxXvonPhkTRe/luTzGwqfWrH/8MQ=",
+    "shasum": "1QLc9RhVgpwxBu8FjPo5kZY61mpNoNAfkiAatq99Nc4=",
     "location": {
       "npm": {
         "filePath": "dist/bundle.js",

packages/examples/packages/ethereum-provider/src/index.ts

@@ -3,7 +3,12 @@ import {
   type OnRpcRequestHandler,
 } from '@metamask/snaps-sdk';
 import type { Hex } from '@metamask/utils';
-import { assert, stringToBytes, bytesToHex } from '@metamask/utils';
+import {
+  assert,
+  stringToBytes,
+  bytesToHex,
+  hexToNumber,
+} from '@metamask/utils';
 
 import type { PersonalSignParams, SignTypedDataParams } from './types';
 
@@ -107,6 +112,9 @@ async function personalSign(message: string, from: string) {
  * @see https://docs.metamask.io/wallet/concepts/signing-methods/#eth_signtypeddata_v4
  */
 async function signTypedData(message: string, from: string) {
+  const chainId = (await ethereum.request<string>({
+    method: 'eth_chainId',
+  })) as string;
   const signature = await ethereum.request<Hex>({
     method: 'eth_signTypedData_v4',
     params: [
@@ -160,7 +168,7 @@ async function signTypedData(message: string, from: string) {
         domain: {
           name: 'Ether Mail',
           version: '1',
-          chainId: 1,
+          chainId: hexToNumber(chainId),
           verifyingContract: '0xCcCCccccCCCCcCCCCCCcCcCccCcCCCcCcccccccC',
         },
         message: {