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

engine/rpcserver_test.go

@@ -1779,7 +1779,7 @@ func TestRPCServer_GetTicker_LastUpdatedNanos(t *testing.T) {
 
 	// Push a mock-up ticker.
 	now := time.Now()
-	ticker.ProcessTicker(&ticker.Price{
+	err = ticker.ProcessTicker(&ticker.Price{
 		ExchangeName: testExchange,
 		Pair:         pair,
 		AssetType:    asset.Spot,
@@ -1790,6 +1790,9 @@ func TestRPCServer_GetTicker_LastUpdatedNanos(t *testing.T) {
 		Low:   169,
 		Close: 196,
 	})
+	if err != nil {
+		t.Fatal(err)
+	}
 
 	// Prepare a ticker request.
 	request := &gctrpc.GetTickerRequest{