fix: improve Etherscan API with proper chainId handling and V1 fallback

- Extract chainId from Network object when available instead of hardcoding to 1 - Add fallback mechanism to handle networks that don't support V2 API yet - Gracefully handle deprecated V1 endpoint responses - Maintain backward compatibility with both string and Network endpoint types This ensures the fix works across all Etherscan network endpoints while providing robust error handling and fallback support.

Author: ci-bot

libs/remix-core-plugin/src/lib/helpers/fetch-etherscan.ts

@@ -11,14 +11,33 @@ export const fetchContractFromEtherscan = async (plugin, endpoint: string | Netw
  if (!etherscanKey) etherscanKey = '2HKUX5ZVASZIKWJM8MIQVCRUVZ6JAWT531'
 
  if (etherscanKey) {
+ // Extract chain ID from Network object before converting to string
+ let chainId = 1 // Default to Ethereum mainnet
  if (typeof endpoint === 'object' && endpoint !== null && 'id' in endpoint && 'name' in endpoint) {
+ chainId = endpoint.id
  endpoint = endpoint.id == 1 ? 'api.etherscan.io' : 'api-' + endpoint.name + '.etherscan.io'
  }
  try {
- // Use V2 API with chainid parameter (defaults to mainnet)
- const chainId = 1 // Default to Ethereum mainnet
- data = await fetch('https://' + endpoint + '/v2/api?chainid=' + chainId + '&module=contract&action=getsourcecode&address=' + contractAddress + '&apikey=' + etherscanKey)
+ // Try V2 API first with chainid parameter
+ let apiUrl = 'https://' + endpoint + '/v2/api?chainid=' + chainId + '&module=contract&action=getsourcecode&address=' + contractAddress + '&apikey=' + etherscanKey
+ data = await fetch(apiUrl)
+ 
+ // If V2 API fails (404 or other error), fallback to V1 API
+ if (!data.ok) {
+ apiUrl = 'https://' + endpoint + '/api?module=contract&action=getsourcecode&address=' + contractAddress + '&apikey=' + etherscanKey
+ data = await fetch(apiUrl)
+ }
+ 
  data = await data.json()
+ 
+ // Handle deprecated V1 endpoint response
+ if (data.message === 'NOTOK' && data.result && data.result.includes('deprecated V1 endpoint')) {
+ // Force V2 API usage even if it initially failed
+ apiUrl = 'https://' + endpoint + '/v2/api?chainid=' + chainId + '&module=contract&action=getsourcecode&address=' + contractAddress + '&apikey=' + etherscanKey
+ data = await fetch(apiUrl)
+ data = await data.json()
+ }
+ 
  // etherscan api doc https://docs.etherscan.io/api-endpoints/contracts
  if (data.message === 'OK' && data.status === "1") {
  if (data.result.length) {