modules/starboard: Add thumbnails of pictures when a file is attached

This prevents seemingly empty starred messages from appearing

modules/starboard/starboard.go

@@ -80,19 +80,26 @@ func ReactListener(s *discordgo.Session, m *discordgo.MessageReactionAdd) {
 		m.GuildID, m.ChannelID, m.MessageID,
 	)
 
-	msg, err = s.ChannelMessageSendEmbed(
-		config.StarChannel,
-		&discordgo.MessageEmbed{
-			Title:       "Starred Message",
-			Description: content,
-			Color:       color,
-			Timestamp:   messageTimestamp.Format(time.RFC3339),
-			Author: &discordgo.MessageEmbedAuthor{
-				Name:    msg.Author.Username + "#" + msg.Author.Discriminator,
-				IconURL: "https://cdn.discordapp.com/avatars/" + msg.Author.ID + "/" + msg.Author.Avatar + ".png",
-			},
+	embed := discordgo.MessageEmbed{
+		Title:       "Starred Message",
+		Description: content,
+		Color:       color,
+		Timestamp:   messageTimestamp.Format(time.RFC3339),
+		Author: &discordgo.MessageEmbedAuthor{
+			Name:    msg.Author.Username + "#" + msg.Author.Discriminator,
+			IconURL: "https://cdn.discordapp.com/avatars/" + msg.Author.ID + "/" + msg.Author.Avatar + ".png",
 		},
-	)
+	}
+	if len(msg.Embeds) > 0 && msg.Embeds[0].Image != nil {
+		img := msg.Embeds[0].Image
+		embed.Thumbnail = &discordgo.MessageEmbedThumbnail{
+			URL:      img.URL,
+			ProxyURL: img.ProxyURL,
+			Width:    img.Width,
+			Height:   img.Height,
+		}
+	}
+	msg, err = s.ChannelMessageSendEmbed(config.StarChannel, &embed)
 	if err != nil {
 		log.Error(s, "listenToStarboardReact", "channelMessageSendEmbed", err)
 		return