@KoihimeNakamura reports that SMAPI throws errors during update checks if no connection is available. Make sure a friendly error is shown instead.

SMAPI currently shows a friendly WARN message followed by the error details in a DEBUG message. When the connection is offline, that results in scary stack traces:

I changed it to detect routine connection errors, and only show the error message instead:

Done in develop for the upcoming SMAPI 2.1 release.