Make character previews not stack trace (#27871)

code/modules/mob/living/carbon/carbon_life.dm

@@ -1,6 +1,9 @@
 /mob/living/carbon/Life(seconds, times_fired)
 	set invisibility = 0
 
+	if(flags & ABSTRACT)
+		return
+
 	if(notransform)
 		return
 

code/modules/mob/living/carbon/carbon_procs.dm

@@ -1,7 +1,7 @@
 /mob/living/carbon/Initialize(mapload)
 	. = ..()
 	GLOB.carbon_list += src
-	if(!loc)
+	if(!loc && !(flags & ABSTRACT))
 		stack_trace("Carbon mob being instantiated in nullspace")
 
 /mob/living/carbon/Destroy()

code/modules/mob/living/carbon/human/human_defines.dm

@@ -107,3 +107,6 @@
 
 	/// Lazylist of sources to track what our alpha should be, alpha is set to the minimum. Use the `set_alpha_tracking` and `get_alpha` helpers.
 	var/list/alpha_sources
+
+/mob/living/carbon/human/fake
+	flags = ABSTRACT