Probably fixes most of the random map test failures (#22571)

ran tests on a loop for like 2 hours while i was doin bits and had no
failures. granted this one will immediately fail for some other
indiscernible reason im sure

1. generate_landing() creates a clearing landmark which has a
late_initialize() to qdel anything it overlaps with. usually it doesn't
overlap with things, but if there's a failure to find an appropriate
landing site, it will just pop it down anywhere. this means it happens
significantly more on more compact sites, like the listening outpost
which seems to fail frequently
2. test runs before gc tick so qdelled stuff has a null location and is
still found `in world`
3. tests loop for `door in world` and find doors at a null location,
which obviously has a null turf, so the test fails
4. in the firedoor test this causes a runtime too because of a missing
assertion

there are probably more reasons map tests fail given they've been
failing for years but this seems to fix a major cause of them

- code_imp: "Door tests skip qdeleted doors, so they should no longer
intermittently fail when landing zone generation clears a ruin."

code/unit_tests/map_tests.dm

@@ -159,6 +159,8 @@
 	var/checks = 0
 	var/failed_checks = 0
 	for(var/obj/structure/machinery/door/airlock/A in world)
+		if(QDELETED(A))
+			continue
 		var/turf/T = get_turf(A)
 		checks++
 		TEST_ASSERT_NOTNULL(T, "A turf does not exist under the door at [A.x],[A.y],[A.z]")
@@ -180,8 +182,11 @@
 	var/checks = 0
 	var/failed_checks = 0
 	for(var/obj/structure/machinery/door/firedoor/F in world)
+		if(QDELETED(F))
+			continue
 		var/turf/T = get_turf(F)
 		checks++
+		TEST_ASSERT_NOTNULL(T, "A turf does not exist under the firedoor at [F.x],[F.y],[F.z]")
 		var/firelock_increment = 0
 		for(var/obj/structure/machinery/door/firedoor/FD in T)
 			firelock_increment += 1

html/changelogs/llywelwyn-maptest-deleted-doors.yml

@@ -0,0 +1,4 @@
+author: Llywelwyn
+delete-after: True
+changes:
+  - code_imp: "Door tests skip qdeleted doors, so they should no longer intermittently fail when landing zone generation clears a ruin."