This error maybe only occur in FA2sp 1.6.X (this situation did not occur in FA2sp 1.5.2 earlier or fa2ext)

At present, it can be concluded that it is a new bug in 1.6.1.

When the Width of the map is equal to or even greater than the Height of the map, and the width and height are equal to or greater than 44, selecting a large Foundation building such as CAOUTP (科技前哨站) or CATHOSP (科技医院) will cause an error when the mouse crosses the bottom right corner of the map.

If the user uses "Shift+drag" instead of previewing and drops a large building to the bottom right corner, the ground editor crashes instantly and saves fcrash_backup.map when "save"(救) map, this error will be brought to the backup map, which will result in an error every time you use FA2sp to open this map unless the last building is deleted in the [Structures] section.

We can try to reproduce this error, should be previewing CATHOSP in the bottom right corner of the map when both the length and width of the map are equal to 45.

The error dialog may appear later. If there are no dialog, you can try changing the map size. This also proves that this bug is a memory issue.

I suspect that the map buffer was too small when creating buffer zone, and a corner of a large building exceeded that memory, causing the compilation to crash.

I did not test the situation inside the game. When entering the game, according to WW's characteristic, there may be internal errors (XD