Graceful error handling for cert expiration

[EnsignPayton]

Yomichan suddenly stopped adding audio to my cards today. This is due to JapanesePod101's SSL cert expiring, which has been reported many times already:

#180 #280 #471 #676 #1216

I'm aware it's a transient issue, users are free to select an alternate audio source, etc. My suggestion is since this is a reoccurring issue, it should be handled with some visible error state to inform the user that something is wrong, and perhaps offer the suggestions of changing audio sources, waiting a day, etc.

I'm sure I'm not the only one over the past few years that made several cards only to find that none of them had audio after the fact, with no indication that anything was wrong on the Yomichan side.

[EnsignPayton]

Wow that was fast, thank you!