4 files changed, 38 insertions, 40 deletions
diff --git a/src/contract_wrappers/contract_wrapper.ts b/src/contract_wrappers/contract_wrapper.ts
index 19dccc6f2..7997b1647 100644
--- a/src/contract_wrappers/contract_wrapper.ts
+++ b/src/contract_wrappers/contract_wrapper.ts
@@ -38,6 +38,29 @@ export class ContractWrapper {
         this._onLogAddedSubscriptionToken = undefined;
         this._onLogRemovedSubscriptionToken = undefined;
     }
+    /**
+     * Cancels all existing subscriptions
+     */
+    public unsubscribeAll(): void {
+        const filterTokens = _.keys(this._filterCallbacks);
+        _.each(filterTokens, filterToken => {
+            this._unsubscribe(filterToken);
+        });
+    }
+    protected _unsubscribe(filterToken: string, err?: Error): void {
+        if (_.isUndefined(this._filters[filterToken])) {
+            throw new Error(ZeroExError.SubscriptionNotFound);
+        }
+        if (!_.isUndefined(err)) {
+            const callback = this._filterCallbacks[filterToken];
+            callback(err, undefined);
+        }
+        delete this._filters[filterToken];
+        delete this._filterCallbacks[filterToken];
+        if (_.isEmpty(this._filters)) {
+            this._stopBlockAndLogStream();
+        }
+    }
     protected _subscribe<ArgsType extends ContractEventArgs>(
         address: string, eventName: ContractEvents, indexFilterValues: IndexedFilterValues, abi: Web3.ContractAbi,
         callback: EventCallback<ArgsType>): string {
@@ -50,16 +73,6 @@ export class ContractWrapper {
         this._filterCallbacks[filterToken] = callback;
         return filterToken;
     }
-    protected _unsubscribe(filterToken: string): void {
-        if (_.isUndefined(this._filters[filterToken])) {
-            throw new Error(ZeroExError.SubscriptionNotFound);
-        }
-        delete this._filters[filterToken];
-        delete this._filterCallbacks[filterToken];
-        if (_.isEmpty(this._filters)) {
-            this._stopBlockAndLogStream();
-        }
-    }
     protected async _getLogsAsync<ArgsType extends ContractEventArgs>(
         address: string, eventName: ContractEvents, subscriptionOpts: SubscriptionOpts,
         indexFilterValues: IndexedFilterValues, abi: Web3.ContractAbi): Promise<Array<LogWithDecodedArgs<ArgsType>>> {
@@ -90,7 +103,7 @@ export class ContractWrapper {
                     ...decodedLog,
                     removed,
                 };
-                this._filterCallbacks[filterToken](logEvent);
+                this._filterCallbacks[filterToken](null, logEvent);
             }
         });
     }
@@ -122,11 +135,18 @@ export class ContractWrapper {
         delete this._blockAndLogStreamer;
     }
     private async _reconcileBlockAsync(): Promise<void> {
-        const latestBlock = await this._web3Wrapper.getBlockAsync(BlockParamLiteral.Latest);
-        // We need to coerce to Block type cause Web3.Block includes types for mempool blocks
-        if (!_.isUndefined(this._blockAndLogStreamer)) {
-            // If we clear the interval while fetching the block - this._blockAndLogStreamer will be undefined
-            this._blockAndLogStreamer.reconcileNewBlock(latestBlock as any as Block);
+        try {
+            const latestBlock = await this._web3Wrapper.getBlockAsync(BlockParamLiteral.Latest);
+            // We need to coerce to Block type cause Web3.Block includes types for mempool blocks
+            if (!_.isUndefined(this._blockAndLogStreamer)) {
+                // If we clear the interval while fetching the block - this._blockAndLogStreamer will be undefined
+                this._blockAndLogStreamer.reconcileNewBlock(latestBlock as any as Block);
+            }
+        } catch (err) {
+            const filterTokens = _.keys(this._filterCallbacks);
+            _.each(filterTokens, filterToken => {
+                this._unsubscribe(filterToken, err);
+            });
         }
     }
 }
diff --git a/src/contract_wrappers/exchange_wrapper.ts b/src/contract_wrappers/exchange_wrapper.ts
index b8704e72c..b608e6931 100644
--- a/src/contract_wrappers/exchange_wrapper.ts
+++ b/src/contract_wrappers/exchange_wrapper.ts
@@ -49,7 +49,6 @@ const SHOULD_VALIDATE_BY_DEFAULT = true;
  */
 export class ExchangeWrapper extends ContractWrapper {
     private _exchangeContractIfExists?: ExchangeContract;
-    private _activeSubscriptions: string[];
     private _orderValidationUtils: OrderValidationUtils;
     private _tokenWrapper: TokenWrapper;
     private _exchangeContractErrCodesToMsg = {
@@ -84,7 +83,6 @@ export class ExchangeWrapper extends ContractWrapper {
         super(web3Wrapper, abiDecoder);
         this._tokenWrapper = tokenWrapper;
         this._orderValidationUtils = new OrderValidationUtils(tokenWrapper, this);
-        this._activeSubscriptions = [];
         this._contractAddressIfExists = contractAddressIfExists;
     }
     /**
@@ -666,7 +664,6 @@ export class ExchangeWrapper extends ContractWrapper {
         const subscriptionToken = this._subscribe<ArgsType>(
             exchangeContractAddress, eventName, indexFilterValues, artifacts.ExchangeArtifact.abi, callback,
         );
-        this._activeSubscriptions.push(subscriptionToken);
         return subscriptionToken;
     }
     /**
@@ -674,7 +671,6 @@ export class ExchangeWrapper extends ContractWrapper {
      * @param   subscriptionToken Subscription token returned by `subscribe()`
      */
     public unsubscribe(subscriptionToken: string): void {
-        _.pull(this._activeSubscriptions, subscriptionToken);
         this._unsubscribe(subscriptionToken);
     }
     /**
@@ -825,13 +821,6 @@ export class ExchangeWrapper extends ContractWrapper {
         const ZRXtokenAddress = await exchangeInstance.ZRX_TOKEN_CONTRACT.callAsync();
         return ZRXtokenAddress;
     }
-    /**
-     * Cancels all existing subscriptions
-     */
-    public unsubscribeAll(): void {
-        _.forEach(this._activeSubscriptions, this._unsubscribe.bind(this));
-        this._activeSubscriptions = [];
-    }
     private async _invalidateContractInstancesAsync(): Promise<void> {
         this.unsubscribeAll();
         delete this._exchangeContractIfExists;
diff --git a/src/contract_wrappers/token_wrapper.ts b/src/contract_wrappers/token_wrapper.ts
index 5d6d61cef..081113964 100644
--- a/src/contract_wrappers/token_wrapper.ts
+++ b/src/contract_wrappers/token_wrapper.ts
@@ -29,13 +29,11 @@ const ALLOWANCE_TO_ZERO_GAS_AMOUNT = 47275;
 export class TokenWrapper extends ContractWrapper {
     public UNLIMITED_ALLOWANCE_IN_BASE_UNITS = constants.UNLIMITED_ALLOWANCE_IN_BASE_UNITS;
     private _tokenContractsByAddress: {[address: string]: TokenContract};
-    private _activeSubscriptions: string[];
     private _tokenTransferProxyContractAddressFetcher: () => Promise<string>;
     constructor(web3Wrapper: Web3Wrapper, abiDecoder: AbiDecoder,
                 tokenTransferProxyContractAddressFetcher: () => Promise<string>) {
         super(web3Wrapper, abiDecoder);
         this._tokenContractsByAddress = {};
-        this._activeSubscriptions = [];
         this._tokenTransferProxyContractAddressFetcher = tokenTransferProxyContractAddressFetcher;
     }
     /**
@@ -262,7 +260,6 @@ export class TokenWrapper extends ContractWrapper {
         const subscriptionToken = this._subscribe<ArgsType>(
             tokenAddress, eventName, indexFilterValues, artifacts.TokenArtifact.abi, callback,
         );
-        this._activeSubscriptions.push(subscriptionToken);
         return subscriptionToken;
     }
     /**
@@ -270,7 +267,6 @@ export class TokenWrapper extends ContractWrapper {
      * @param   subscriptionToken Subscription token returned by `subscribe()`
      */
     public unsubscribe(subscriptionToken: string): void {
-        _.pull(this._activeSubscriptions, subscriptionToken);
         this._unsubscribe(subscriptionToken);
     }
     /**
@@ -294,13 +290,6 @@ export class TokenWrapper extends ContractWrapper {
         );
         return logs;
     }
-    /**
-     * Cancels all existing subscriptions
-     */
-    public unsubscribeAll(): void {
-        _.forEach(this._activeSubscriptions, this._unsubscribe.bind(this));
-        this._activeSubscriptions = [];
-    }
     private _invalidateContractInstancesAsync(): void {
         this.unsubscribeAll();
         this._tokenContractsByAddress = {};
diff --git a/src/types.ts b/src/types.ts
index a9eac56d8..af3c36736 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -41,8 +41,8 @@ export type OrderValues = [BigNumber, BigNumber, BigNumber,
 export interface LogEvent<ArgsType> extends LogWithDecodedArgs<ArgsType> {
     removed: boolean;
 }
-export type EventCallbackAsync<ArgsType> = (log: LogEvent<ArgsType>) => Promise<void>;
-export type EventCallbackSync<ArgsType> = (log: LogEvent<ArgsType>) => void;
+export type EventCallbackAsync<ArgsType> = (err: null|Error, log?: LogEvent<ArgsType>) => Promise<void>;
+export type EventCallbackSync<ArgsType> = (err: null|Error, log?: LogEvent<ArgsType>) => void;
 export type EventCallback<ArgsType> = EventCallbackSync<ArgsType>|EventCallbackAsync<ArgsType>;
 export interface ExchangeContract extends Web3.ContractInstance {
     isValidSignature: {