[Client Crash] - Crash after setting invalid entity to net_entity

[Muche]

Bug Submission:

Category: Client Crash

Issue Title: Crash after setting invalid entity to net_entity

Issue Description:

Setting an entity that has been removed (thus is currently invalid) to net_entity causes hard crash.

Also removing an entity assigned to net_entity sets the net_entity's value to nil, but dirty event is not fired.

Steps to Reproduce:

Host a world with following mod enabled:

local function getdbgstr(inst)
	local str = tostring(inst)
	if inst ~= nil and inst.IsValid ~= nil then
		str = str .. "; IsValid=" .. tostring(inst:IsValid())
	end
	return str
end

local function getnetdbgstr(net_var)
	local str = tostring(net_var)
	if net_var ~= nil then
		local val = net_var:value()
		str = str .. ", value=" .. getdbgstr(val) 
	end
	return str
end

local function do3(inst)
	print("[TestMod:do3]#1 inst.net_testentity=" .. getnetdbgstr(inst.net_testentity))
	local axe = inst.testentity
	print("[TestMod:do3]#2 axe=" .. getdbgstr(axe))
	inst.net_testentity:set(axe)
	print("[TestMod:do3]#3 inst.net_testentity=" .. getnetdbgstr(inst.net_testentity))
	print("[TestMod:do3]#4 inst.testentity=" .. getdbgstr(inst.testentity))
end

local function do2(inst)
	print("[TestMod:do2]#1 inst.net_testentity=" .. getnetdbgstr(inst.net_testentity))
	local entity = inst.net_testentity:value()
	if entity ~= nil then
		entity:Remove()
	end
	print("[TestMod:do2]#2 inst.net_testentity=" .. getnetdbgstr(inst.net_testentity))
	print("[TestMod:do2]#3 inst.testentity=" .. getdbgstr(inst.testentity))

	inst:DoTaskInTime(10, do3)
end

local function do1(inst)
	print("[TestMod:do1]#1 inst.net_testentity=" .. getnetdbgstr(inst.net_testentity))
	local axe = GLOBAL.SpawnPrefab("axe")
	inst.net_testentity:set(axe)
	inst.testentity = axe
	print("[TestMod:do1]#2 inst.net_testentity=" .. getnetdbgstr(inst.net_testentity))
	print("[TestMod:do1]#3 inst.testentity=" .. getdbgstr(inst.testentity))

	inst:DoTaskInTime(10, do2)
end

local function OnTestEntityDirty(inst)
	print("[TestMod:OnTestEntityDirty]#1 inst.net_testentity=" .. getnetdbgstr(inst.net_testentity))
	print("[TestMod:OnTestEntityDirty]#2 inst.testentity=" .. getdbgstr(inst.testentity))
end

AddPrefabPostInit("player_classified", function(inst)
	inst.net_testentity = GLOBAL.net_entity(inst.GUID, "test.entity", "test.entitydirty")
	print("[TestMod:postinit] inst.net_testentity=" .. getnetdbgstr(inst.net_testentity))
	inst:ListenForEvent("test.entitydirty", OnTestEntityDirty)

	inst:DoTaskInTime(10, do1)
end)

It produces following log:

[00:00:31]: [TestMod:postinit] inst.net_testentity=net_entity (5D737798), value=nil	
[00:00:41]: [TestMod:do1]#1 inst.net_testentity=net_entity (5D737798), value=nil	
[00:00:41]: [TestMod:do1]#2 inst.net_testentity=net_entity (5D737798), value=109193 - axe; IsValid=true	
[00:00:41]: [TestMod:do1]#3 inst.testentity=109193 - axe; IsValid=true	
[00:00:41]: [TestMod:OnTestEntityDirty]#1 inst.net_testentity=net_entity (5D737798), value=109193 - axe; IsValid=true	
[00:00:41]: [TestMod:OnTestEntityDirty]#2 inst.testentity=109193 - axe; IsValid=true	
[00:00:51]: [TestMod:do2]#1 inst.net_testentity=net_entity (5D737798), value=109193 - axe; IsValid=true	
[00:00:51]: [TestMod:do2]#2 inst.net_testentity=net_entity (5D737798), value=nil	
[00:00:51]: [TestMod:do2]#3 inst.testentity=109193 - axe; IsValid=false	
[00:01:01]: [TestMod:do3]#1 inst.net_testentity=net_entity (5D737798), value=nil	
[00:01:01]: [TestMod:do3]#2 axe=109193 - axe; IsValid=false	

after that hard crash occurs - dontstarve_steam_162028_crash_2016_1_11T0_26_18C0.zip

Also notice that dirty event is fired only once (on change from nil to axe), but not on change from axe to nil.