unrecoverable failure WRT loading maps in RMT when TMX is down

[XertroV]

This bug can occur when a map is selected via RMT that is not uploaded to nadeo services and TMX is down.

(I assume there's code to deal with the case when TMX is not down).

The bug results in a softlock and is unrecoverable.

As a partial mitigation, I've uploaded (to nadeo) all TMX maps that had not been uploaded. This should, for the most part, avoid this bug.

In general, it would be good to have some code to handle when a map isn't available via tmx (it might be requestable from nadeo via UID, or available via a mirror). The RMT case is a bit different, but easier to solve by just ensuring everything is uploaded in advance.