Add missing onError callbacks

packages/website/ts/blockchain.ts

@@ -375,7 +375,11 @@ export class Blockchain {
                 clearInterval(this._zrxPollIntervalId);
                 delete this._zrxPollIntervalId;
             }
-        }, 5000);
+        }, 5000, (err: Error) => {
+            utils.consoleLog(`Polling tokenBalance failed: ${err}`);
+            clearInterval(this._zrxPollIntervalId);
+            delete this._zrxPollIntervalId;
+        });
     }
     public async signOrderHashAsync(orderHash: string): Promise<SignatureData> {
         utils.assert(!_.isUndefined(this._zeroEx), 'ZeroEx must be instantiated.');

packages/website/ts/web3_wrapper.ts

@@ -1,6 +1,7 @@
 import { BigNumber, intervalUtils, promisify } from '@0xproject/utils';
 import * as _ from 'lodash';
 import { Dispatcher } from 'ts/redux/dispatcher';
+import { utils } from 'ts/utils/utils';
 import * as Web3 from 'web3';
 
 export class Web3Wrapper {
@@ -135,7 +136,10 @@ export class Web3Wrapper {
                     await this._updateUserEtherBalanceAsync(this._prevUserAddress);
                 }
             }
-        }, 5000);
+        }, 5000, (err: Error) => {
+            utils.consoleLog(`Watching network and balances failed: ${err}`);
+            this._stopEmittingNetworkConnectionAndUserBalanceStateAsync();
+        });
     }
     private async _updateUserEtherBalanceAsync(userAddress: string) {
         const balance = await this.getBalanceInEthAsync(userAddress);