message: don't send blank messages
diff: @@ -581,8 +581,13 @@ export class DiscordBot {
  await this.store.Insert(evt);
  });
  });
  - if (msg.content !== null) {
  + if (msg.content === null) {
  + return;
  + }
  const result = await this.msgProcessor.FormatDiscordMessage(msg);
  + if (!result.body) {
  + return;
  + }
  await Util.AsyncForEach(rooms, async (room) => {
  const trySend = async () => intent.sendMessage(room, {
  body: result.body,
  @@ -612,7 +617,6 @@ export class DiscordBot {
  await afterSend(res);
  }
  });
  - }
  } catch (err) {
  log.verbose("Failed to send message into room.", err);
  }
  