[MIRROR] ports a bunch of grep checks from TG (#10361)

Co-authored-by: Kashargul <144968721+Kashargul@users.noreply.github.com>
Co-authored-by: Cameron Lennox <killer65311@gmail.com>

code/game/objects/effects/blockers_yw.dm

@@ -9,4 +9,4 @@
 /obj/effect/mobblocker/CanPass(atom/movable/mover, turf/target)
 	if(istype(mover, /mob/living/simple_mob))
 		return FALSE
-	return TRUE
+	return TRUE

code/game/objects/effects/decals/posters/bs12.dm

@@ -346,4 +346,3 @@
 	name = "space carp information poster"
 	desc = "This poster showcases an old spacer saying on the dangers of migrant space carp."
 	listing_name = "Safety - Carp Information"
-

code/game/objects/effects/landmarks_vr.dm

@@ -1,4 +1,4 @@
-  
+
 /obj/effect/landmark
 	var/abductor = 0