Adds a unit test to check for any missing initial icon states (#8332)

code/game/objects/structures/crates_lockers/closets/secure/security.dm

@@ -441,6 +441,7 @@
 /obj/structure/closet/secure_closet/wall
 	name = "wall locker"
 	req_access = list(access_security)
+	icon = 'icons/obj/walllocker.dmi'
 	icon_state = "wall-locker1"
 	density = 1
 	icon_closed = "wall-locker"

code/game/objects/structures/door_assembly.dm

@@ -132,6 +132,7 @@
 
 /obj/structure/door_assembly/multi_tile
 	icon = 'icons/obj/doors/door_assembly2x1.dmi'
+	icon_state = null //only have icons for the glass version
 	dir = EAST
 	var/width = 1
 

code/game/objects/structures/signs.dm

@@ -194,7 +194,7 @@
 /obj/structure/sign/directions
 	name = "direction sign"
 	desc = "A direction sign, claiming to know the way."
-	icon_state = "direction"
+	icon_state = null
 
 /obj/structure/sign/directions/science
 	name = "\improper Science department"

code/game/objects/structures/window.dm

@@ -448,8 +448,8 @@
 /obj/structure/window/phoronreinforced/skrell
 	name = "advanced borosilicate-alloy window"
 	desc = "A window made out of a higly advanced borosilicate alloy. It seems to be extremely strong."
-	basestate = "skrell_phoronwindow"
-	icon_state = "skrell_phoronwindow"
+	basestate = "phoronwindow"
+	icon_state = "phoronwindow"
 	maxhealth = 250
 
 /obj/structure/window/reinforced