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/binance/binance.go

@@ -743,7 +743,13 @@ func (b *Binance) SendAuthHTTPRequest(ePath exchange.URL, method, path string, p
 		fullPath := endpointPath + path
 		params.Set("timestamp", strconv.FormatInt(time.Now().Unix()*1000, 10))
 		signature := params.Encode()
-		hmacSigned := crypto.GetHMAC(crypto.HashSHA256, []byte(signature), []byte(b.API.Credentials.Secret))
+		var hmacSigned []byte
+		hmacSigned, err = crypto.GetHMAC(crypto.HashSHA256,
+			[]byte(signature),
+			[]byte(b.API.Credentials.Secret))
+		if err != nil {
+			return nil, err
+		}
 		hmacSignedStr := crypto.HexEncodeToString(hmacSigned)
 		headers := make(map[string]string)
 		headers["X-MBX-APIKEY"] = b.API.Credentials.Key

exchanges/binance/binance_test.go

@@ -1331,7 +1331,10 @@ 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() || mockTests {
 		if feeBuilder.FeeType != exchange.OfflineTradeFee {
 			t.Errorf("Expected %v, received %v", exchange.OfflineTradeFee, feeBuilder.FeeType)