network connection with updated web3

remix-lib/src/execution/execution-context.js

@@ -279,8 +279,8 @@ function ExecutionContext () {
     } else {
       web3.setProvider(new web3.providers.HttpProvider(endpoint))
     }
-    // fixed
+    web3.eth.net.isListening((err, isConnected) => {
-    if (web3.isConnected()) {
+      if (!err && isConnected) {
         executionContext = context
         self._updateBlockGasLimit()
         self.event.trigger('contextChanged', ['web3'])
@@ -292,6 +292,7 @@ function ExecutionContext () {
         alertMsg += 'Make sure the provider is running and a connection is open (via IPC or RPC).'
         cb(alertMsg)
       }
+    })
   }
   this.setProviderFromEndpoint = setProviderFromEndpoint