Detect traps numbers showing up in unexplored areas

[Grond]

Sometimes detect traps numbers show up in unexplored areas. In one case, after digging out the area, the numbers remained and indicated traps where there were no traps.

[Krzysztof Dycha]

Not sure if this is AGE or Unity, assigning Jochen just in case

[Jochen Terstiege]

Trap hints were not removed when the map changed.