I encountered a bug where the player is being forced out of his spidertron engineer when a water tile block from Waterfill mod is being placed below it.

Error MainLoop.cpp:1207: Exception at tick 23030559: The mod Spidertron Engineer (1.6.2) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event SpidertronEngineer::on_gui_closed (ID 85)
LuaEntity API call when LuaEntity was invalid.
stack traceback:
SpidertronEngineer/control.lua:589: in function <SpidertronEngineer/control.lua:585>
stack traceback:
[C]: in function 'index'
__SpidertronEngineer/control.lua:589: in function <SpidertronEngineer/control.lua:585>

link to the mod with placable water tiles: https://mods.factorio.com/mod/Waterfill_v17

I'm wondering if its possible to restrict any form of block placement below the spider (eg: landfill, waterfall, etc..) to prevent similar situation from happening.

Thanks for the report. I'll add a hook that catches when the spidertron engineer has been destroyed and also kill the player. I don't think that there is any way to prevent the water being placed beneath the spidertron (without this mod, that would simply kill the player)

thank you, that will be nicer than a crash XD

Fixed in 1.6.3. As a bonus, because it is the spidertron that is destroyed, not the player, it allows me to kill the player so that you can still retrieve his items! (It isn't possible to do the same to the spidertron because by the time I get the 'destroyed' event, its inventory is already gone).