Fixed channelsToIDCache not being initialized

pkg/twitch/twitch.go

@@ -22,7 +22,8 @@ type Client struct {
 // NewClient returns a new Client with the provided clientID
 func NewClient(clientID string) *Client {
 	return &Client{
-		ClientID: clientID,
+		ClientID:          clientID,
+		channelsToIDCache: make(map[string]string),
 	}
 }