Bug when placing second floor

Summary: trying to place a second floor.

Steps to reproduce:

  1. place wall
  2. choose second floor tool
  3. make square and release button

Expected Results:
placed floor
Actual Results:
bug report popup
Notes:
release-707 (x64)
radiant/modules/entities.lua:317: attempt to index local ‘entity’ (a nil value)
stack traceback:
[C]: ?
radiant/modules/entities.lua:317: in function 'get_world_grid_location’
stonehearth/services/server/build/build_service.lua:589: in function '_subtract_region_from_floor’
stonehearth/services/server/build/build_service.lua:319: in function '_add_floor_type’
stonehearth/services/server/build/build_service.lua:269: in function 'add_floor’
stonehearth/services/server/build/build_service.lua:153: in function 'cb’
stonehearth/services/server/build/build_service.lua:1583: in function 'do_command’
stonehearth/services/server/build/build_service.lua:152: in function <stonehearth/services/server/build/build_service.lua:150>

page 2:
release-707 (x64)
c++ exception: lua runtime error
stack traceback:

Attachments:

Version Number and Mods in use: vanilla

System Information: windows 10 x64

Tried placing second floor again:
release-707 (x64)
…ehearth/services/server/build/build_undo_manager.lua:46: assertion failed!
stack traceback:
[C]: ?
[C]: in function ‘assert’
…ehearth/services/server/build/build_undo_manager.lua:46: in function 'begin_transaction’
stonehearth/services/server/build/build_service.lua:1580: in function 'do_command’
stonehearth/services/server/build/build_service.lua:152: in function <stonehearth/services/server/build/build_service.lua:150>

trying to delete the building:
release-707 (x64)
…ehearth/services/server/build/build_undo_manager.lua:414: assertion failed!
stack traceback:
[C]: ?
[C]: in function ‘assert’
…ehearth/services/server/build/build_undo_manager.lua:414: in function 'clear’
stonehearth/services/server/build/build_service.lua:121: in function 'set_teardown’
stonehearth/call_handlers/build_call_handler.lua:25: in function <stonehearth/call_handlers/build_call_handler.lua:23>

could you add some pictures, if possible?
And after starting the game you can see, in the lower left corner, the version number.