diff --git a/remix-lib/src/execution/execution-context.js b/remix-lib/src/execution/execution-context.js
index ce3d23b504..0e1b2dc313 100644
--- a/remix-lib/src/execution/execution-context.js
+++ b/remix-lib/src/execution/execution-context.js
@@ -1,28 +1,25 @@
 /* global ethereum */
 'use strict'
-var Web3 = require('web3')
-var EventManager = require('../eventManager')
-var EthJSVM = require('ethereumjs-vm').default
-var ethUtil = require('ethereumjs-util')
-var StateManager = require('ethereumjs-vm/dist/state/stateManager').default
-var Web3VMProvider = require('../web3Provider/web3VmProvider')
+const Web3 = require('web3')
+const EventManager = require('../eventManager')
+const EthJSVM = require('ethereumjs-vm').default
+const ethUtil = require('ethereumjs-util')
+const StateManager = require('ethereumjs-vm/dist/state/stateManager').default
+const Web3VMProvider = require('../web3Provider/web3VmProvider')
 
-var LogsManager = require('./logsManager.js')
+const LogsManager = require('./logsManager.js')
 
-var rlp = ethUtil.rlp
+const rlp = ethUtil.rlp
 
-var injectedProvider
-
-var web3
 if (typeof window !== 'undefined' && typeof window.web3 !== 'undefined') {
-  injectedProvider = window.web3.currentProvider
-  web3 = new Web3(injectedProvider)
+  var injectedProvider = window.web3.currentProvider
+  var web3 = new Web3(injectedProvider)
 } else {
   web3 = new Web3(new Web3.providers.HttpProvider('http://localhost:8545'))
 }
 
-var blankWeb3 = new Web3()
-
+const blankWeb3 = new Web3()
+const currentFork = 'istanbul'
 /*
   extend vm state manager and instanciate VM
 */
@@ -143,7 +140,7 @@ function ExecutionContext () {
   }
 
   this.web3 = function () {
-    return this.isVM() ? vms.istanbul.web3vm : web3
+    return this.isVM() ? vms[currentFork].web3vm : web3
   }
 
   this.detectNetwork = function (callback) {
@@ -198,7 +195,7 @@ function ExecutionContext () {
   }
 
   this.vm = function () {
-    return vms.istanbul.vm
+    return vms[currentFork].vm
   }
 
   this.setContext = function (context, endPointUrl, confirmCb, infoCb) {
@@ -211,8 +208,8 @@ function ExecutionContext () {
 
     if (context === 'vm') {
       executionContext = context
-      vms.istanbul.stateManager.revert(() => {
-        vms.istanbul.stateManager.checkpoint(() => {})
+      vms[currentFork].stateManager.revert(() => {
+        vms[currentFork].stateManager.checkpoint(() => {})
       })
       self.event.trigger('contextChanged', ['vm'])
       return cb()
diff --git a/remix-lib/src/execution/txRunner.js b/remix-lib/src/execution/txRunner.js
index 60580e3378..dece547e90 100644
--- a/remix-lib/src/execution/txRunner.js
+++ b/remix-lib/src/execution/txRunner.js
@@ -148,7 +148,8 @@ class TxRunner {
     executionContext.vm().runBlock({ block: block, generate: true, skipBlockValidation: true, skipBalance: false }).then(function (results) {
       let result = results.results[0]
       if (result) {
-        result.status = '0x' + (result.execResult.exceptionError ? 0 : 1)
+        const status = result.execResult.exceptionError ? 0 : 1
+        result.status = `0x${status}`
       }
       executionContext.addBlock(block)
       executionContext.trackTx('0x' + tx.hash().toString('hex'), block)
@@ -157,7 +158,6 @@ class TxRunner {
         transactionHash: ethJSUtil.bufferToHex(Buffer.from(tx.hash()))
       })
     }).catch(function (err) {
-      err = err ? err.message : err
       callback(err)
     })
   }
diff --git a/remix-lib/src/web3Provider/web3VmProvider.js b/remix-lib/src/web3Provider/web3VmProvider.js
index 1e0211d10e..716d71a38a 100644
--- a/remix-lib/src/web3Provider/web3VmProvider.js
+++ b/remix-lib/src/web3Provider/web3VmProvider.js
@@ -126,7 +126,8 @@ web3VmProvider.prototype.txProcessed = function (self, data) {
   }
   self.txsReceipt[self.processingHash].logs = logs
   self.txsReceipt[self.processingHash].transactionHash = self.processingHash
-  self.txsReceipt[self.processingHash].status = '0x' + (data.execResult.exceptionError ? 0 : 1)
+  const status = data.execResult.exceptionError ? 0 : 1
+  self.txsReceipt[self.processingHash].status = `0x${status}`
 
   if (data.createdAddress) {
     var address = util.hexConvert(data.createdAddress)