linter: Enable error checking linter (#766)

* golangci: Enable err checking linter to expose unchecked errors.

* gct: handle errors across the board

* gct: handle errors NOTE: Found bug in FTX (WIP)

* linter: fix issues

* ftx/exchanges: fix bug where error was being returned when setting pair management variables to an already enabled state

* bitmex: fix bug where a dangly supported asset in config danglied up the place.

* linter: fix more linter issues

* linter: fix my terrible spelling.

* currency: fix test

* exchanges: fix tests

* logger: fix test

* exchanges: fix tests

* glorious: nits

* vm: revert rm variable and instigate test

exchanges/bittrex/bittrex.go

@@ -386,9 +386,18 @@ func (b *Bittrex) SendAuthHTTPRequest(ep exchange.URL, method, action string, pa
 			}
 		}
 		body = bytes.NewBuffer(payload)
-		contentHash = crypto.HexEncodeToString(crypto.GetSHA512(payload))
+		hash, err := crypto.GetSHA512(payload)
+		if err != nil {
+			return nil, err
+		}
+		contentHash = crypto.HexEncodeToString(hash)
 		sigPayload := ts + endpoint + path + method + contentHash
-		hmac = crypto.GetHMAC(crypto.HashSHA512, []byte(sigPayload), []byte(b.API.Credentials.Secret))
+		hmac, err = crypto.GetHMAC(crypto.HashSHA512,
+			[]byte(sigPayload),
+			[]byte(b.API.Credentials.Secret))
+		if err != nil {
+			return nil, err
+		}
 
 		headers := make(map[string]string)
 		headers["Api-Key"] = b.API.Credentials.Key

exchanges/bittrex/bittrex_test.go

@@ -339,7 +339,10 @@ func setFeeBuilder() *exchange.FeeBuilder {
 // TestGetFeeByTypeOfflineTradeFee logic test
 func TestGetFeeByTypeOfflineTradeFee(t *testing.T) {
 	var feeBuilder = setFeeBuilder()
-	b.GetFeeByType(feeBuilder)
+	_, err := b.GetFeeByType(feeBuilder)
+	if err != nil {
+		t.Fatal(err)
+	}
 	if !areTestAPIKeysSet() {
 		if feeBuilder.FeeType != exchange.OfflineTradeFee {
 			t.Errorf("Expected %v, received %v", exchange.OfflineTradeFee, feeBuilder.FeeType)

exchanges/bittrex/bittrex_websocket.go

@@ -155,11 +155,15 @@ func (b *Bittrex) WsAuth() error {
 		return err
 	}
 	timestamp := strconv.FormatInt(time.Now().UnixNano()/1000000, 10)
-	hmac := crypto.GetHMAC(
+	hmac, err := crypto.GetHMAC(
 		crypto.HashSHA512,
 		[]byte(timestamp+randomContent.String()),
 		[]byte(b.API.Credentials.Secret),
 	)
+	if err != nil {
+		return err
+	}
+
 	signature := crypto.HexEncodeToString(hmac)
 
 	req := WsEventRequest{

exchanges/bittrex/bittrex_wrapper.go

@@ -144,7 +144,10 @@ func (b *Bittrex) Setup(exch *config.ExchangeConfig) error {
 		return nil
 	}
 
-	b.SetupDefaults(exch)
+	err := b.SetupDefaults(exch)
+	if err != nil {
+		return err
+	}
 
 	wsRunningEndpoint, err := b.API.Endpoints.GetURL(exchange.WebsocketSpot)
 	if err != nil {

exchanges/bittrex/bittrex_ws_orderbook.go

@@ -166,7 +166,10 @@ func (b *Bittrex) applyBufferUpdate(pair currency.Pair) error {
 				"%s error processing update - initiating new orderbook sync via REST: %s\n",
 				b.Name,
 				err)
-			b.obm.setNeedsFetchingBook(pair)
+			err = b.obm.setNeedsFetchingBook(pair)
+			if err != nil {
+				return err
+			}
 		}
 	}
 	return nil