wrap forking initialization errors with contextual info

lib/forking/forked_blockchain.js

@@ -168,15 +168,18 @@ ForkedBlockchain.prototype.initialize = async function(accounts, callback) {
   try {
     const forkVersion = await new Promise((resolve, reject) => {
       this.web3.eth.net.getId((err, version) => {
-        err ? reject(err) : resolve(version);
+        err ? reject(new Error(`The fork provider errored when checking net_version: ${err}`)) : resolve(version);
       });
     });
 
     this.forkVersion = forkVersion;
 
     const forkBlock = (this.forkBlock = await new Promise((resolve, reject) => {
-      this.web3.eth.getBlock(this.forkBlockNumber || "latest", (err, json) => {
-        err ? reject(err) : resolve(json);
+      const queriedBlock = this.forkBlockNumber || "latest";
+      this.web3.eth.getBlock(queriedBlock, (err, json) => {
+        err
+          ? reject(new Error(`The fork provider errored when checking for block '${queriedBlock}': ${err}`))
+          : resolve(json);
       });
     }));
 
@@ -197,7 +200,11 @@ ForkedBlockchain.prototype.initialize = async function(accounts, callback) {
       accounts.map((account) => {
         return new Promise((resolve, reject) => {
           this.web3.eth.getTransactionCount(account.address, this.forkBlockNumber, (err, nonce) => {
-            err ? reject(err) : resolve(nonce);
+            err
+              ? reject(
+                new Error(`The fork provider errored when checking the nonce for account ${account.address}: ${err}`)
+              )
+              : resolve(nonce);
           });
         });
       })