Avoid deleting reminders silently

[wookie184]

Currently a reminder will be ignored+deleted if the bot cannot get the channel it was meant to reply in:

bot/bot/exts/utils/reminders.py

Lines 112 to 124 in 324cb65

	def ensure_valid_reminder(self, reminder: dict) -> tuple[bool, discord.TextChannel]:
	"""Ensure reminder channel can be fetched otherwise delete the reminder."""
	channel = self.bot.get_channel(reminder["channel_id"])
	is_valid = True
	if not channel:
	is_valid = False
	log.info(
	f"Reminder {reminder['id']} invalid: "
	f"Channel {reminder['channel_id']}={channel}."
	)
	scheduling.create_task(self.bot.api_client.delete(f"bot/reminders/{reminder['id']}"))
	return is_valid, channel

This could happen if the remind command was run in a thread, or a channel that was deleted.

There are a couple of options here:

• Don't allow the command in threads, or always send the reminder to e.g. #bot-commands
• Send the reminder to e.g. #bot-commands if it failed to send. Is it ok to send reminders that may have been run in a private channel to a public channel though?
• Try to DM the reminder to the user(s) - DMs may not always be open though
• Just tell them the reminder failed to send in #bot-commands - avoids ever leaking anything and is simple, but they don't get the contents.

This is an edge case so I think whatever the solution it should be as simple as possible, just something better than not reminding the user(s) at all.