Update EtherscanProvider to use their v2 API (#4975).

Author: ricmoo

src.ts/providers/provider-etherscan.ts

@@ -144,9 +144,6 @@ export class EtherscanProvider extends AbstractProvider {
         this.#plugin = network.getPlugin<EtherscanPlugin>(EtherscanPluginId);
 
         defineProperties<EtherscanProvider>(this, { apiKey, network });
-
-        // Test that the network is supported by Etherscan
-        this.getBaseUrl();
     }
 
     /**
@@ -155,6 +152,11 @@ export class EtherscanProvider extends AbstractProvider {
      *  If an [[EtherscanPlugin]] is configured on the
      *  [[EtherscanBaseProvider_network]], returns the plugin's
      *  baseUrl.
+     *
+     *  Deprecated; for Etherscan v2 the base is no longer a simply
+     *  host, but instead a URL including a chainId parameter. Changing
+     *  this to return a URL prefix could break some libraries, so it
+     *  is left intact but will be removed in the future as it is unused.
      */
     getBaseUrl(): string {
         if (this.#plugin) { return this.#plugin.baseUrl; }
@@ -202,22 +204,22 @@ export class EtherscanProvider extends AbstractProvider {
      *  Returns the URL for the %%module%% and %%params%%.
      */
     getUrl(module: string, params: Record<string, string>): string {
-        const query = Object.keys(params).reduce((accum, key) => {
+        let query = Object.keys(params).reduce((accum, key) => {
             const value = params[key];
             if (value != null) {
                 accum += `&${ key }=${ value }`
             }
             return accum
         }, "");
-        const apiKey = ((this.apiKey) ? `&apikey=${ this.apiKey }`: "");
-        return `${ this.getBaseUrl() }/api?module=${ module }${ query }${ apiKey }`;
+        if (this.apiKey) { query += `&apikey=${ this.apiKey }`; }
+        return `https:/\/api.etherscan.io/v2/api?chainid=${ this.network.chainId }&module=${ module }${ query }`;
     }
 
     /**
      *  Returns the URL for using POST requests.
      */
     getPostUrl(): string {
-        return `${ this.getBaseUrl() }/api`;
+        return `https:/\/api.etherscan.io/v2/api?chainid=${ this.network.chainId }`;
     }
 
     /**
@@ -226,6 +228,7 @@ export class EtherscanProvider extends AbstractProvider {
     getPostData(module: string, params: Record<string, any>): Record<string, any> {
         params.module = module;
         params.apikey = this.apiKey;
+        params.chainid = this.network.chainId;
         return params;
     }
 
@@ -367,7 +370,6 @@ export class EtherscanProvider extends AbstractProvider {
      *  Throws the normalized Etherscan error.
      */
     _checkError(req: PerformActionRequest, error: Error, transaction: any): never {
-
         // Pull any message out if, possible
         let message = "";
         if (isError(error, "SERVER_ERROR")) {