[21Moon] Allow upgrade of tiles touching the Rift (without P3)

[jederimo]

This is a very minor bug, I'll admit. Just noting it for a rainy day. Maybe this will be the issue where I start contributing on git :)

What's your Game ID?
238239

How to Reproduce the Bug?

(also described on BGG with designer's thumbs up to roseundy's reply "this seems like a bug": https://boardgamegeek.com/thread/3252654/article/47192087#47192087 )

A company (ITC) owning P3 (Space Bridge Company) built tile F6 to the rift. P3 subsequently closed before the bridge was built. The tile touching the rift (F6) is now not able to be upgraded (by a different company, SWP), even to add track branching away from the rift.

Clicking the tile brings up no green tile options, indicating the tile cannot be upgraded. FYI odd and maybe unrelated: if my 1st tile action lays the last of a type of green tile, this type now appears grayed out when clicking F6 as the 2nd tile action.

Which Browser / Platform?

Multiple. Brave on Android 16 (Pixel 10 Pro).
Brave v1.86.142 (chromium 144.0.7559.97) on Win11.

[ollybh]

This is probably the same problem as in 1837 issue #11692. In that one an impassable border is introduced during the game, and it is not possible to upgrade any tiles that have been laid with track that ends at the border.

The solution would be to tweak the checks that are made when a tile is upgraded: don't reject a tile with track that ends at an impassable edge if this is existing track.