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/bitstamp/bitstamp.go

@@ -631,9 +631,15 @@ func (b *Bitstamp) SendAuthenticatedHTTPRequest(ep exchange.URL, path string, v2
 
 		values.Set("key", b.API.Credentials.Key)
 		values.Set("nonce", n)
-		hmac := crypto.GetHMAC(crypto.HashSHA256,
+
+		var hmac []byte
+		hmac, err = crypto.GetHMAC(crypto.HashSHA256,
 			[]byte(n+b.API.Credentials.ClientID+b.API.Credentials.Key),
 			[]byte(b.API.Credentials.Secret))
+		if err != nil {
+			return nil, err
+		}
+
 		values.Set("signature", strings.ToUpper(crypto.HexEncodeToString(hmac)))
 
 		var fullPath string

exchanges/bitstamp/bitstamp_test.go

@@ -44,7 +44,10 @@ func TestGetFeeByTypeOfflineTradeFee(t *testing.T) {
 	t.Parallel()
 
 	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",

exchanges/bitstamp/bitstamp_websocket.go

@@ -81,7 +81,12 @@ func (b *Bitstamp) wsHandleData(respRaw []byte) error {
 		if b.Verbose {
 			log.Debugf(log.ExchangeSys, "%v - Websocket reconnection request received", b.Name)
 		}
-		go b.Websocket.Shutdown() // Connection monitor will reconnect
+		go func() {
+			err := b.Websocket.Shutdown()
+			if err != nil {
+				log.Errorf(log.WebsocketMgr, "%s failed to shutdown websocket: %v", b.Name, err)
+			}
+		}() // Connection monitor will reconnect
 	case "data":
 		wsOrderBookTemp := websocketOrderBookResponse{}
 		err := json.Unmarshal(respRaw, &wsOrderBookTemp)