I get this error message when I try to change what's being produced in an assembler. Only workaround I know of is to deconstruct the assembler and place a new one.

The scenario level caused a non-recoverable error.
Please report this error to the scenario author.

Error while running event level::on_player_main_inventory_changed (ID 32)
LuaInventory doesn't contain key hasbar.
stack traceback:
...Data/Roaming/Factorio/temp/currently-playing/control.lua:102: in function 'dropItems'
...Data/Roaming/Factorio/temp/currently-playing/control.lua:88: in function <...Data/Roaming/Factorio/temp/currently-playing/control.lua:30>
stack traceback:
[C]: in function '__index'
...Data/Roaming/Factorio/temp/currently-playing/control.lua:102: in function 'dropItems'
...Data/Roaming/Factorio/temp/currently-playing/control.lua:88: in function <...Data/Roaming/Factorio/temp/currently-playing/control.lua:30>

Yep , me too same error.

Error while running event level::on_player_cursor_stack_changed (ID 29)
LuaInventory doesn't contain key hasbar.
stack traceback:
...Data/Roaming/Factorio/temp/currently-playing/control.lua:102: in function 'dropItems'
...Data/Roaming/Factorio/temp/currently-playing/control.lua:436: in function <...Data/Roaming/Factorio/temp/currently-playing/control.lua:426>
stack traceback:
[C]: in function '__index'
...Data/Roaming/Factorio/temp/currently-playing/control.lua:102: in function 'dropItems'
...Data/Roaming/Factorio/temp/currently-playing/control.lua:436: in function <...Data/Roaming/Factorio/temp/currently-playing/control.lua:426>

I have a fix for ya on this. I've reproduced failures in dropItems when stone is destroyed. It seems that putting a ghost roboport on tops of stone, or fighting and stone being destroyed, or running over stone in a tank can cause this to be called with no entity.
In the bottom of dropItems function add this one line - certainly no danger, and I assure you it will remove alot of random crashes, which tend to happen late game:

    if count > 0 then
        -- now we're forced to spill items
        entity = entity or global.forces[player.force.name].roboport
        if (entity.valid) then
            entity.surface.spill_item_stack(entity.position, {name = name, count = count}, false, entity.force, false)
        end
    end

The only addition to that code is checking entity.valid. The only consequence is your tanks may get some stone in them.

That's interesting. So the problem is that the entity that's causing the spill doesn't have a surface at the time the spill occurs. That's good to know.

Slight revision of the code to handle a very odd corner case:

    if count > 0 then
        -- now we're forced to spill items
        entity = entity or global.forces[player.force.name].roboport
        if entity and entity.valid then                    
             if (entity.name ~= "entity-ghost") then
                 entity.surface.spill_item_stack(entity.position, {name = name, count = count}, false, entity.force, false)
            end
        end
    end

no real differences there - sorry, I can't delete that second code post