Exception when holding bag and closing door, bag disappears.

[scrain777]

Using version 1.0, with server hosted on Windows 10. To replicate, hold a bag in your hand. Attempt to close a door. Expected behavior is that the door closes. Acceptable behavior would be to place the bag in front of the door. Actual behavior is that the bag disappears forever, with its contents lost. Server logs:
2020-05-23 20:00:31: ACTION[Server]: player [name] (id=[id], hp=20) punched LuaEntitySAO at (408,31,483) (id=1125, hp=4), damage=0
2020-05-23 20:00:56: ERROR[Server]: [mobs] bad velocity in nil
Code should include exception handling to ensure bag is not lost.

[scrain777]

I did some further investigation. The open door is typically in a solid wall, and the placement code selects a location forward of the open door, which is inside the wall. Then a bug in minetest (minetest/minetest#4759) makes it appear that the bag was placed when it was not.

Relevant code:

   local obj = minetest.env:add_entity(pos, "prestibags:bag_entity")
   if not obj then return stack end

The add_entity returns a reference even though the bag was not added.