[VM] cleanup some changes made in the TangerineWhistle PR

Author: jochem-brouwer

packages/vm/lib/evm/opFns.ts

@@ -680,12 +680,9 @@ export const handlers: { [k: string]: OpHandler } = {
         runState.eei.useGas(new BN(runState._common.param('gasPrices', 'callNewAccount')))
       }
     } else if (!(await runState.stateManager.accountExists(toAddressBuf))) {
-      // We are before Spurious Dragon
+      // We are before Spurious Dragon and the account does not exist.
       // Call new account gas: account does not exist (it is not in the state trie, not even as an "empty" account)
-      const accountDoesNotExist = !(await runState.stateManager.accountExists(toAddressBuf))
-      if (accountDoesNotExist) {
-        runState.eei.useGas(new BN(runState._common.param('gasPrices', 'callNewAccount')))
-      }
+      runState.eei.useGas(new BN(runState._common.param('gasPrices', 'callNewAccount')))
     }
 
     if (!value.isZero()) {

packages/vm/lib/state/cache.ts

@@ -54,27 +54,23 @@ export default class Cache {
   /**
    * Looks up address in underlying trie.
    * @param address - Address of account
-   * @param create - Create emtpy account if non-existent
    */
-  async _lookupAccount(address: Buffer, create: boolean = true): Promise<Account | undefined> {
+  async _lookupAccount(address: Buffer): Promise<Account> {
     const raw = await this._trie.get(address)
-    if (raw || create) {
-      const account = new Account(raw)
-      return account
-    }
+    const account = new Account(raw)
+    return account
   }
 
   /**
    * Looks up address in cache, if not found, looks it up
    * in the underlying trie.
    * @param key - Address of account
-   * @param create - Create emtpy account if non-existent
    */
-  async getOrLoad(key: Buffer, create: boolean = true): Promise<Account | undefined> {
+  async getOrLoad(key: Buffer): Promise<Account> {
     let account = this.lookup(key)
 
     if (!account) {
-      account = await this._lookupAccount(key, create)
+      account = await this._lookupAccount(key)
       if (account) {
         this._update(key, account as Account, false, false)
       }

packages/vm/lib/state/interface.ts

@@ -10,7 +10,7 @@ export interface StorageDump {
 export interface StateManager {
   copy(): StateManager
   getAccount(address: Buffer): Promise<Account>
-  putAccount(address: Buffer, account: Account | null): Promise<void>
+  putAccount(address: Buffer, account: Account): Promise<void>
   deleteAccount(address: Buffer): Promise<void>
   touchAccount(address: Buffer): void
   putContractCode(address: Buffer, value: Buffer): Promise<void>

packages/vm/lib/state/stateManager.ts

@@ -89,6 +89,11 @@ export default class DefaultStateManager implements StateManager {
     this.touchAccount(address)
   }
 
+  /**
+   * Deletes an [`@ethereumjs/account`](https://github.com/ethereumjs/ethereumjs-vm/tree/master/packages/account)
+   * from state under the provided `address`. The account will also be removed from the state trie.
+   * @param address - Address of the account which should be deleted
+   */
   async deleteAccount(address: Buffer) {
     this._cache.del(address)
     this.touchAccount(address)
@@ -115,7 +120,7 @@ export default class DefaultStateManager implements StateManager {
     const codeHash = keccak256(value)
 
     if (codeHash.equals(KECCAK256_NULL)) {
-      //return
+      return
     }
 
     const account = await this.getAccount(address)